* acgeneral.m4 (AC_HASBEEN): New macro. Same as AC_OBSOLETE, but
dies.
* acspecific.m4 (AC_UNISTD_H, AC_USG, AC_MEMORY_H, AC_INT_16_BITS,
AC_LONG_64_BITS): Promoted from obsolete to hasbeen.
* autoheader.m4 (AC_DEFINE_UNQUOTED): Define via AC_DEFINE, so
that we program things only once.
(AC_DEFINE): Use AC_WRAP and _AC_SH_QUOTE. It is now safe to have
backquotes and extra spaces in the third argument, without
yielding a bad result.
* autoheader.m4: Instead of a huge `eval', use a temporary file.
(option handling): Added --debug, to keep the temporary files.
Fixed a couple of missing quotes.