glx: automake: include builddir prior to srcdir

Analogous to previous commit.

Cc: "12.0 13.0" <mesa-dev@lists.freedesktop.org>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
(cherry picked from commit d66f9e6d930a9fcfa23129dce18d5359cc6e00f4)
1 file changed