Original commit message from CVS: - CHECK_LIBHEADER macro, which is based on GST_CHECK_LIBHEADER the main difference between them is that you can specify cpp flags with CHECK_LIBHEADER
All aclocal .m4 files we need are put here and cat'd to acinclude.m4 in the source root. Official ones (taken from the relevant devel packages) are named as-is, unofficial ones (or changed ones) get a gst-prefix.