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().

lib/package/INIT.html

@@ -412,7 +412,7 @@ All recorded changes follow.
 	 regress.sh: INPUT and OUTPUT handle -f for printf instead of print
 04-06-11 package.sh: make sure $INSTALLROOT/bin is in front of $PATH
 	 package.sh: skip nmake if older than 2000-10-31
-04-05-20 package.sh: fix arg vs. package parse with - or '' to disambuguate
+04-05-20 package.sh: fix arg vs. package parse with - or '' to disambiguate
 04-05-11 package.sh: package verbose update lists closure for package setup
 	 package.sh: add src/lib/libardir to nmake proto bootstrap
 	 regress.sh: probe for rm -u vs. chmod -R u+rwx
@@ -480,7 +480,7 @@ All recorded changes follow.
 03-09-23 ratz.c: fix tar header number parse bug that skipped to next number
 	 regress.sh: rm cleanup now handles files matching -*
 03-09-11 iffe.sh: add unnamed { ... } blocks
-	 regress.sh: add COPY from to, like MOVE but comprison still done
+	 regress.sh: add COPY from to, like MOVE but comparison still done
 	 regress.sh: rm -rfu to handle test dirs w/o u+rwx
 03-08-14 Makefile: add hello.c to the manifest
 03-08-11 package.sh: fix `html binary' generation
@@ -579,7 +579,7 @@ All recorded changes follow.
 	 make.probe: add CC.LD.STRIP for link time a.out strip
 	 package.sh: fix package_use vs. PACKAGE_USE check
 02-10-24 WWW.mk: fix bug that required a :WWWBIN: assertion to post
-02-10-23 mamake.c: fix unuinitialized time in make()
+02-10-23 mamake.c: fix uninitialized time in make()
 	 ratz.c: fix meter buffer overflow
 02-10-20 package.sh: fix lib/probe/C/make/probe update test
 02-10-18 probe.win32: update for mingw
@@ -661,7 +661,7 @@ All recorded changes follow.
 	 package.sh: add check for { cc ar nm yacc/bison } before make
 	 ratz.c: fix "rb" vs. "r" macro tests
 	 iffe.sh: add nxt, similar to lcl but defines _nxt_foo for #include
-	 iffe.sh,package.sh: remove vaibale from sccs,cvs ident strings -- duh
+	 iffe.sh,package.sh: remove variable from sccs,cvs ident strings -- duh
 02-01-24 C+probe: check CC.DYNAMIC to handle cc that accept but ignore -B*
 	 iffe.sh: handle 'mem struct.a.b'
 02-01-22 iffe.sh: cache (internal) `foo vs. struct foo' test results
@@ -912,7 +912,7 @@ All recorded changes follow.
 98-05-01 regress: fix bug sometimes didn't list last test
 98-04-01 hostinfo: add cc path arg
 	 hostinfo: now works with /bin/sh
-	 Makefile: strengthed -lm probe
+	 Makefile: strengthen -lm probe
 98-01-23 Makefile: check for -ldl -lm
 	 C.probe: handle gcc -v -E phony include dirs
 	 iffe: fix lcl by dropping sort -u -- we need the real first