Rather than manually include m4 files in configure.ac, let aclocal
do its thing and manage aclocal.m4 automatically for us.
Change-Id: I50689ec78a85651949aab104e7f4de46b14bca5a
Reviewed-on: https://chromium-review.googlesource.com/438544
Reviewed-by: Mark Mentovai <mark@chromium.org>