- according to the automake manual, `acinclude.m4' is the old style
of doing stuff, putting local macros in their own directory is the
way to go, so move acincluce.m4 to m4/windowmaker.m4
- reflect this in autogen.sh and Makefile.am
- while there, add a `conditionally set cflags' macro from the
autoconf macro archive
- use this to slightly pump warning levels up if we are on gcc
