Fix more compiler warnings, typos and other minor issues (#260)

Many of these changes are minor typo fixes. The other changes
(which are mostly compiler warning fixes) are:

NEWS:
- The --globcasedetect shell option works on older Linux kernels
  when used with FAT32/VFAT file systems, so remove the note about
  it only working with 5.2+ kernels.

src/cmd/ksh93/COMPATIBILITY:
- Update the documentation on function scoping with an addition
  from ksh93v- (this does apply to ksh93u+).

src/cmd/ksh93/edit/emacs.c:
- Check for '_AST_ksh_release', not 'AST_ksh_release'.

src/cmd/INIT/mamake.c,
src/cmd/INIT/ratz.c,
src/cmd/INIT/release.c,
src/cmd/builtin/pty.c:
- Add more uses of UNREACHABLE() and noreturn, this time for the
  build system and pty.

src/cmd/builtin/pty.c,
src/cmd/builtin/array.c,
src/cmd/ksh93/sh/name.c,
src/cmd/ksh93/sh/nvtype.c,
src/cmd/ksh93/sh/suid_exec.c:
- Fix six -Wunused-variable warnings (the name.c nv_arrayptr()
  fixes are also in ksh93v-).
- Remove the unused 'tableval' function to fix a -Wunused-function
  warning.

src/cmd/ksh93/sh/lex.c:
- Remove unused 'SHOPT_DOS' code, which isn't enabled anywhere.
  https://github.com/att/ast/issues/272#issuecomment-354363112

src/cmd/ksh93/bltins/misc.c,
src/cmd/ksh93/bltins/trap.c,
src/cmd/ksh93/bltins/typeset.c:
- Add dictionary generator function declarations for former
  aliases that are now builtins (re: 1fbbeaa1, ef1621c1, 3ba4900e).
- For consistency with the rest of the codebase, use '(void)'
  instead of '()' for print_cpu_times.

src/cmd/ksh93/sh/init.c,
src/lib/libast/path/pathshell.c:
- Move the otherwise unused EXE macro to pathshell() and only
  search for 'sh.exe' on Windows.

src/cmd/ksh93/sh/xec.c,
src/lib/libast/include/ast.h:
- Add an empty definition for inline when compiling with C89.
  This allows the timeval_to_double() function to be inlined.

src/cmd/ksh93/include/shlex.h:
- Remove the unused 'PIPESYM2' macro.

src/cmd/ksh93/tests/pty.sh:
- Add '# err_exit #' to count the regression test added in
  commit 113a9392.

src/lib/libast/disc/sfdcdio.c:
- Move diordwr, dioread, diowrite and dioexcept behind
  '#ifdef F_DIOINFO' to fix one -Wunused-variable warning and
  multiple -Wunused-function warnings (sfdcdio() only uses these
  functions when F_DIOINFO is defined).

src/lib/libast/string/fmtdev.c:
- Fix two -Wimplicit-function-declaration warnings on Linux by
  including sys/sysmacros.h in fmtdev().

src/cmd/ksh93/data/builtins.c

@@ -357,7 +357,7 @@ const char sh_optalias[] =
 	"to see whether it is an alias.]"
 "[+?If no \aname\as are specified then the names and values of all "
 	"aliases are written to standard output.  Otherwise, for "
-	"each \aname\a that is specified, and \b=\b\avalue\a  is not "
+	"each \aname\a that is specified, and \b=\b\avalue\a is not "
 	"specified, the current value of the alias corresponding to "
 	"\aname\a is written to standard output.  If \b=\b\avalue\a is "
 	"specified, the alias \aname\a will be created or redefined.]" 
@@ -876,7 +876,7 @@ _JOB_
 "\n[job ...]\n"
 "\n"
 "[+EXIT STATUS?If \bfg\b brings one or more jobs into the foreground, "
-	"the exit status of \bfg\b  will be that of the last \ajob\a.  "
+	"the exit status of \bfg\b will be that of the last \ajob\a.  "
 	"If one or more jobs does not exist or has completed, \bfg\b will "
 	"return a non-zero exit status.]"
 "}"
@@ -1374,7 +1374,7 @@ const char sh_optpwd[] =
 "[+DESCRIPTION?\bpwd\b writes an absolute pathname of the current working "
 	"directory to standard output.   An absolute pathname is a "
 	"pathname that begins with \b/\b that does not contains any "
-	"\b.\b  or \b..\b components.]"
+	"\b.\b or \b..\b components.]"
 "[+?If both \b-L\b and \b-P\b are specified, the last one specified will "
 	"be used.  If neither \b-P\b or \b-L\b is specified then the "
 	"behavior will be determined by the \bgetconf\b parameter "
@@ -1777,7 +1777,7 @@ const char sh_opttypeset[] =
 	"assigned before the attributes are set.]"
 "[+?When \btypeset\b is called inside a function defined with the "
 	"\bfunction\b reserved word, and \aname\a does not contain a "
-	"\b.\b, then a local variable statically scoped to  that function "
+	"\b.\b, then a local variable statically scoped to that function "
 	"will be created.]"
 "[+?Not all option combinations are possible.  For example, the numeric "
 	"options \b-i\b, \b-E\b, and \b-F\b cannot be specified with "
@@ -1844,7 +1844,7 @@ const char sh_opttypeset[] =
 	"value will be displayed as an unsigned integer.]"
 "[x?Puts each \aname\a on the export list.  See \bexport\b(1).  \aname\a "
 	"cannot contain a \b.\b.]"
-"[A?Associative array.  Each \aname\a will converted to an associative "
+"[A?Associative array.  Each \aname\a is converted to an associative "
 	"array.  If a variable already exists, the current value will "
 	"become index \b0\b.]"
 "[C?Compound variable.  Each \aname\a will be a compound variable.  If "
@@ -1976,7 +1976,7 @@ const char sh_optunset[] =
 "[-1c?\n@(#)$Id: unset (AT&T Research) 1999-07-07 $\n]"
 "[--catalog?" SH_DICT "]"
 "[+NAME?unset - unset values and attributes of variables and functions]"
-"[+DESCRIPTION?For each \aname\a specified, \bunset\b  unsets the variable, "
+"[+DESCRIPTION?For each \aname\a specified, \bunset\b unsets the variable, "
 	"or function if \b-f\b is specified, from the current shell "
 	"execution environment.  Readonly variables cannot be unset.]"
 "[n?If \aname\a refers to variable that is a reference, the variable \aname\a "
@@ -2037,7 +2037,7 @@ _JOB_
 "\n"
 "[+EXIT STATUS?If \await\a is invoked with one or more \ajob\as, and all of "
 	"them have terminated or were not known by the invoking shell, "
-	"the exit status of \bwait\b  will be that of the last \ajob\a.  "
+	"the exit status of \bwait\b will be that of the last \ajob\a.  "
 	"Otherwise, it will be one of the following:]{"
 	"[+0?\bwait\b utility was invoked with no operands and all "
 		"processes known by the invoking process have terminated.]"

src/cmd/ksh93/data/lexstates.c

@@ -411,7 +411,7 @@ const char e_lexlabunknown[]	= "line %d: %s unknown label";
 const char e_lexobsolete1[]	= "line %d: `...` obsolete, use $(...)";
 const char e_lexobsolete2[]	= "line %d: -a obsolete, use -e";
 const char e_lexobsolete3[]	= "line %d: '=' obsolete, use '=='";
-const char e_lexobsolete4[]	= "line %d: %s within [[...]] obsolete, use ((...))";
+const char e_lexobsolete4[]	= "line %d: %s within [[ ... ]] obsolete, use ((...))";
 const char e_lexobsolete5[]	= "line %d: set %s obsolete";
 const char e_lexobsolete6[]	= "line %d: `{' instead of `in' is obsolete";
 const char e_lexusebrace[]	= "line %d: use braces to avoid ambiguities with $id[...]";

src/cmd/ksh93/data/strdata.c

@@ -27,7 +27,7 @@
 #include	"streval.h"
 
 const unsigned char strval_precedence[35] =
-	/* opcode	precedence,assignment  */
+	/* opcode	precedence,assignment */
 {
 	/* DEFAULT */		MAXPREC|NOASSIGN,
 	/* DONE */		0|NOASSIGN|RASSOC,