a few edits around configure.ac area

AC_HEADER_STDBOOL complaint should disappear here: https://github.com/fontforge/fontforge/issues/384#issuecomment-14449167
...seems more talk about it here too with gnuplot, so something maybe needs upgrading concerning the autoconf process:
http://www.mail-archive.com/autoconf@gnu.org/msg21553.html

Removed a python dependency for a is_LIGATURES.[ch] files that can be built using another program like unicode/maketype.c or makebuildtables.c which already parse through the unicode info. This info should be updated when unicode info goes-up a rev.