Move custom macros to acinclude.m4 so we can autogenerate aclocal.m4
with aclocal. This matches every other project in the tree.
libiberty/ChangeLog:
* Makefile.in (ACLOCAL, ACLOCAL_AMFLAGS, $(srcdir)/aclocal.m4): Define.
(configure_deps): Rename to ...
(aclocal_deps): ... this. Replace aclocal.m4 with acinclude.m4.
($(srcdir)/configure): Replace $(configure_deps) with
$(srcdir)/aclocal.m4.
* aclocal.m4: Move libiberty macros to acinclude.m4, then regenerate.
* acinclude.m4: New file.
* configure: Regenerate.
