Thank you for all the information in the Autoconf manual about replacing "obsoleted" macros. A couple comments.
AC_FUNC_VFORK is warned about, but not mentioned in the manual anywhere. Maybe it should be another @itemx with AC_VFORK. AC_PROG_LEX is warned about when used without an option. But the behavior with no options cannot be replicated with either option. So it seems like it should not be considered obsolete? Even if the behavior was "due to a bug". Such is reality. AC_HEADER_TIME is complained about, but the additional #definition of TIME_WITH_SYS_TIME makes it different than the replacement. Again this seems like it is not obsolete as a result. I can't imagine many maintainers would be happy spending time tinkering with time.h vs. sys/time.h code that has worked forever just because there's a new Autoconf macro. Best, Karl P.S. Just FYI: with Autoconf 2.71 (unlike 2.70), TeX Live built again without any changes to the configure.ac/Makefile.am/etc. files. Thanks!