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/sh.1

@@ -3951,7 +3951,7 @@ using \fB\s+2.\s-2\fP\f2identifier\fP\fB\s+2.\s-2\fP\f2name\fP.
 Similarly, a function defined by a command in the
 .B namespace
 .I list\^
-is created using the name space name  preceded by a \fB\s+2.\s-2\fP.
+is created using the name space name preceded by a \fB\s+2.\s-2\fP.
 .PP
 When  the
 .I list\^
@@ -4314,7 +4314,7 @@ being searched.
 .P
 The
 .B .paths
-file is then checked  for a line of the form
+file is then checked for a line of the form
 .BI PLUGIN_LIB= libname
 \*(OK \f3:\fP \f2libname\^\fP \*(CK .\|.\|. .
 Each library named by
@@ -6145,7 +6145,7 @@ and IEEE POSIX 1003.2 standards.
 (See
 .IR pathconf (2)
 and
-.IR sysconf (2).)
+.IR sysconf (3).)
 The
 .I pathname
 argument is required for parameters whose value depends on
@@ -7479,7 +7479,7 @@ or
 \f3times\fP
 Displays the accumulated user and system CPU times, one line with the times
 used by the shell and another with those used by all of the shell's child
-processes. No options are supporetd.
+processes. No options are supported.
 .TP
 \(dg \f3trap\fP \*(OK \f3\-p\fP \*(CK \*(OK \f2action\^\fP \*(CK \*(OK \f2sig\^\fP \*(CK .\|.\|.
 The
@@ -8445,7 +8445,7 @@ except that the following are disallowed:
 .RS
 .PD 0
 .PP
-Unsetting the restricted option.
+unsetting the restricted option,
 .br
 changing directory (see
 .IR cd (1)),
@@ -8470,9 +8470,9 @@ redirecting output
 .BR >| ,
 .BR <> ,
 and
-.BR >> ).
+.BR >> ) ,
 .br
-adding or deleting built-in commands.
+adding or deleting built-in commands,
 .br
 using
 .B "command -p"
@@ -8591,7 +8591,7 @@ lseek(2),
 paste(1),
 pathconf(2),
 pipe(2),
-sysconf(2),
+sysconf(3),
 umask(2),
 ulimit(2),
 wait(2),