add missing ACLOCAL_AMFLAGS

This package puts m4 files in config/ but doesn't set the right -I flags
which leads to random errors with autoreconf.  Declare it properly.

BUG=chromium-os:39738
TEST=`emerge-x86-alex dbus-c++` still works

Change-Id: I0235cb96eb184a4c5b18c24ef6e32382e5493d81
Reviewed-on: https://gerrit.chromium.org/gerrit/45037
Reviewed-by: Chris Masone <cmasone@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
1 file changed