Support building via autoconf and automake. mkfiles.pl now outputs a

Makefile.am, and there's a new mkauto.sh which builds a corresponding
configure script.

The old makefile has been renamed from 'Makefile' to 'Makefile.gtk',
indicating that the intended new _default_ approach is to use the
autoconf world. Makefile.gtk is provided as an emergency fallback in
case anything fails with the new stuff that used to work with it.

The new configure script does not support the same $(BINPREFIX) system
as the old Makefile did. However, as I understand it, it should be
possible to configure using --program-prefix="sgt-" (for example) and
then the binaries should all be renamed appropriately at install time.

The Makefile.am is quite painful. The Puzzles codebase relies heavily
on compiling individual object files multiple times with different the
cpp flags per build deliverable (program or library) and not per
source file. Solution: anything built with non-default compile options
has to go in its own little library. But that doesn't work either in
the general case, because as soon as you have more than one such
library linked into an application, Unix ld semantics bite you if the
objects in the libraries both refer to each other. So I ended up
building all those little libraries but not _using_ them - instead the
link commands for the programs needing those objects refer to the
objects directly, under the silly names that automake gives them.
(That's less fragile than it sounds, because it does _document_ the
names of the intermediate object files. But still, yuck.)

[originally from svn r9886]

Recipe

@@ -8,7 +8,8 @@
 
 !name puzzles
 
-!makefile gtk Makefile
+!makefile gtk Makefile.gtk
+!makefile am Makefile.am
 !makefile vc Makefile.vc
 !makefile wce Makefile.wce
 !makefile cygwin Makefile.cyg
@@ -130,6 +131,22 @@ version2.def: FORCE
 .PHONY: FORCE
 !end
 !specialobj gtk version
+# In the automake build, we have to do the whole job by supplying
+# extra CFLAGS, so we have to put the if statement inside one big
+# backtick expression. We also force rebuilding via a -D option that
+# makes version.o include empty.h, which we construct ourselves and
+# touch whenever any source file is updated.
+!cflags am version $(VER) -DINCLUDE_EMPTY_H `if test -z "$(VER)" && (cd $(srcdir)/..; md5sum -c manifest >/dev/null 2>&1); then cat $(srcdir)/../version.def; else echo "$(VER)"; fi`
+!begin am
+BUILT_SOURCES = empty.h
+CLEANFILES = empty.h
+empty.h: $(allsources)
+	echo '/* Empty file touched by automake makefile to force rebuild of version.o */' >$@
+
+!end
+!begin >empty.h
+/* Empty file touched by automake makefile to force rebuild of version.o */
+!end
 !begin nestedvm
 version.o: version.c version2.def
 	$(CC) $(COMPAT) $(XFLAGS) $(CFLAGS) `cat version2.def` -c version.c