Add ‘@CFLAGS@’, ‘@CPPFLAGS@’, and ‘@LDFLAGS@’ in your Makefile.in files, so they can take advantage of the values of those variables in the environment when configure is run. Doing this isn't necessary, but it's a convenience for users.
Also add ‘@configure_input@’ in a comment to each input file for
AC_OUTPUT, so that the output files contain a comment saying
they were produced by configure. Automatically selecting the
right comment syntax for all the kinds of files that people call
AC_OUTPUT on became too much work.
Add config.log and config.cache to the list of files you
remove in distclean targets.
If you have the following in Makefile.in:
prefix = /usr/local
exec_prefix = $(prefix)
you must change it to:
prefix = @prefix@
exec_prefix = @exec_prefix@
The old behavior of replacing those variables without ‘@’ characters around them has been removed.