Build system: make SHOPT_* editable again; allow indenting Mamfiles

The build system is adapted to make SHOPT_* compile-time options
editable without nmake. We can now easily change ksh's compile-time
options by editing src/cmd/ksh93/SHOPT.sh. The bin/package script
is adapted to turn these into compile flags. This resolves the most
important drawback of not using nmake.

Also, mamake now has support for indented Mam (Make Abstract
Machine) code. Only one type of block (make...done) is supported in
Mamfiles, so they are easy to indent automatically. A script to
(re)do this is included.

Since nmake is not going to be restored (it has too many problems
that no one is interested in fixing), this at least makes mamake
significantly easier to work with.

The Makefiles are deleted. They may still be handy for reference to
understand the Mamfiles, but they haven't actually matched the
Mamfiles for a while -- and you can still look in the git history.

Deleting them requires some adaptations to bin/package and mamake.c
because, even though they do not use those files, they still looked
for them to decide whether to build code in a directory.

Finally, this commit incorporates some #pragmas for clang to
suppress annoying warnings about the coding style used in this
historic code base. (gcc does not complain so much.)

src/cmd/ksh93/SHOPT.sh:
- Added.

bin/package, src/cmd/INIT/package.sh:
- cd into our own directory in case we were run from another dir.
- $makefiles: only look for Mamfiles.
- Add ksh compile-options via KSH_SHOPTFLAGS. Include SHOPT.sh.
- make_recurse(): Do not write a missing Makefile.
- finalize environment: Look for Mamfiles instead of Makefiles.

src/cmd/INIT/mamake.c:
- Tell clang to suppress annoying warnings about coding style.
- Update version string and self-documentation.
- input(): Add support for indented Mam code by skipping initial
  whitespace on each input line.
- files[]: Instead of looking for various of Makefiles to decide
  where to build, only look for Mamfiles.

src/Makefile, src/cmd/INIT/Makefile, src/cmd/Makefile,
src/cmd/builtin/Makefile, src/cmd/ksh93/Makefile, src/lib/Makefile,
src/lib/libast/Makefile, src/lib/libcmd/Makefile,
src/lib/libdll/Makefile, src/lib/libsum/Makefile:
- Removed.

src/Mamfile, src/cmd/INIT/Mamfile, src/cmd/Mamfile,
src/cmd/builtin/Mamfile, src/cmd/ksh93/Mamfile, src/lib/Mamfile,
src/lib/libast/Mamfile, src/lib/libcmd/Mamfile,
src/lib/libdll/Mamfile, src/lib/libsum/Mamfile:
- Indent the code with tabs.
- In ksh93/Mamfile, add ${KSH_SHOPT_FLAGS} to every $CC command.
- In ksh93/Mamfile, add "prev SHOPT.sh" for every *.o file
  so they are rebuilt whenever SHOPT.sh changes.

bin/Mamfile_indent:
- Added, in case someone wants to re-indent a Mamfile.

src/cmd/INIT/proto.c, src/cmd/INIT/ratz.c, src/cmd/INIT/release.c,
src/lib/libast/features/common, src/lib/libast/include/ast.h:
- Tell clang to suppress annoying warnings about coding style that
  it disapproves of (mainly concerning the use of parentheses).

src/cmd/INIT/cc.darwin, src/cmd/INIT/cc.freebsd,
src/cmd/INIT/cc.openbsd:
- Remove now-redundant clang warning suppression flags.

Resolves: https://github.com/ksh93/ksh/issues/60

bin/package

@@ -31,6 +31,29 @@ Bad*)	echo "Cannot be run by zsh in native mode; use a sh symlink to zsh" >&2
 	exit 1 ;;
 esac
 
+unset CDPATH
+case $0 in
+-*)
+	echo "dodgy \$0: $0" >&2
+	exit 1 ;;
+*/package)
+	mydir=`echo "$0" | sed 's,/package$,,'`
+	cd "$mydir" || exit
+	case $PWD in
+	*/bin)	;;
+	*)	echo "this script must live in bin/" >&2
+		exit 1 ;;
+	esac
+	cd .. || exit
+	unset mydir ;;
+package)
+	echo "this script must be invoked with a direct path, e.g. bin/package" >&2
+	exit 1 ;;
+*)
+	echo "this script must be named 'package'" >&2
+	exit 1 ;;
+esac
+
 # shell checks
 checksh()
 {
@@ -64,7 +87,7 @@ usr="/home"
 lib="" # nee /usr/local/lib /usr/local/shlib
 ccs="/usr/kvm /usr/ccs/bin"
 org="gnu GNU"
-makefiles="Mamfile Nmakefile nmakefile Makefile makefile"
+makefiles="Mamfile"  # ksh 93u+m no longer uses these: Nmakefile nmakefile Makefile makefile
 env="HOSTTYPE NPROC PACKAGEROOT INSTALLROOT PATH"
 checksum=md5sum
 checksum_commands="$checksum md5"
@@ -1405,6 +1428,20 @@ case $ksh_relflags in
 	assign="${assign:+$assign }KSH_RELFLAGS=\"\$ksh_relflags\"" ;;
 esac
 
+# Add ksh compile-options via KSH_SHOPTFLAGS.
+SHOPT()
+{
+	case $1 in
+	*=?*)	ksh_shoptflags="${ksh_shoptflags:+$ksh_shoptflags }-DSHOPT_$1" ;;
+	esac
+}
+ksh_shoptflags=
+. src/cmd/ksh93/SHOPT.sh	# this script calls SHOPT() to set options
+case $ksh_shoptflags in
+?*)	# add the extra flags as an argument to mamake
+	assign="${assign:+$assign }KSH_SHOPTFLAGS=\"\$ksh_shoptflags\"" ;;
+esac
+
 # grab action specific args
 
 case $action in
@@ -4037,12 +4074,6 @@ make_recurse() # dir
 		then	return
 		fi
 	done
-	if	test -d $1
-	then	case $exec in
-		'')	echo :MAKE: > $1/Makefile || exit ;;
-		*)	$exec "echo :MAKE: > $1/Makefile" ;;
-		esac
-	fi
 }
 
 get() # host path [ file size ]
@@ -7218,7 +7249,7 @@ update)	# download the latest release.version for selected packages
 use)	# finalize the environment
 
 	x=:..
-	for d in `( cd $PACKAGEROOT; ls src/*/Makefile src/*/Nmakefile 2>/dev/null | sed 's,/[^/]*$,,' | sort -u )`
+	for d in `( cd $PACKAGEROOT; ls src/*/Mamfile 2>/dev/null | sed 's,/[^/]*$,,' | sort -u )`
 	do	x=$x:$INSTALLROOT/$d
 	done
 	x=$x:$INSTALLROOT