* m4/calloc.m4 (_AC_FUNC_CALLOC_IF):
* m4/malloc.m4 (_AC_FUNC_MALLOC_IF):
* m4/realloc.m4 (_AC_FUNC_REALLOC_IF):
Avoid some unnecessary differences from Autoconf’s versions.
Separate our platforms into a different line so that it’s easier
to diff. Use AS_IF in case the args use AC_REQUIRE.
However, don’t bother with omitting the first newline, as
omitting the newline is not Gnulib style and the difference
doesn’t seem to matter here.