autogen.sh is reporting some warnings as below
./autogen.sh 2>&1 |grep "obsolete"
libtoolize: copying file 'm4/lt~obsolete.m4'
configure.ac:115: warning: The macro `AC_LANG_C' is obsolete.
configure.ac:115: warning: The macro `AC_TRY_COMPILE' is obsolete.
configure.ac:134: warning: The macro `AC_LANG_C' is obsolete.
configure.ac:134: warning: The macro `AC_TRY_COMPILE' is obsolete.
configure.ac:135: warning: The macro `AC_LANG_C' is obsolete.
configure.ac:135: warning: The macro `AC_TRY_COMPILE' is obsolete.
configure.ac:146: warning: The macro `AC_LANG_C' is obsolete.
configure.ac:146: warning: The macro `AC_TRY_COMPILE' is obsolete.
configure.ac:146: warning: The macro `AC_LANG_C' is obsolete.
configure.ac:146: warning: The macro `AC_TRY_COMPILE' is obsolete.
configure.ac:373: warning: The macro `AC_LANG_C' is obsolete.
configure.ac:373: warning: The macro `AC_TRY_COMPILE' is obsolete.
configure.ac:458: warning: The macro `AC_HEADER_TIME' is obsolete.
configure.ac:681: warning: The macro `AC_TRY_LINK' is obsolete.
configure.ac:807: warning: The macro `AC_TRY_LINK' is obsolete.
As the minimum autoconf version required is v2.69,
we need to make sure to update obsolete macros as described at
https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Obsolete-Macros.html
- 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
