The configure scripts were regenerated with 2.69 for the newlib-4.2.0
release in 484d2ebf8d, but the aclocal
files were not. Do that now to avoid confusion between the two as to
which version of autoconf was used.
Since automake deprecated the INCLUDES name in favor of AM_CPPFLAGS,
change all existing users over. The generated code is the same since
the two variables have been used in the same exact places by design.
There are other cleanups to be done, but lets focus on just renaming
here so we can upgrade to a newer automake version w/out triggering
new warnings.