build: use git ls-files for adding all Makefile.in into the release tarball

Until we have proper 'make dist' this is an improvement of the current
situation, because each time some old Makefiles got converted to automake
we had to update the tarballs target.

NOTE: This is a candidate for the 9.0 branch.

Cc: Eric Anholt <eric@anholt.net>
Acked-by: Matt Turner <mattst88@gmail.com>
diff --git a/Makefile.am b/Makefile.am
index b22458e..1f4fcac 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -85,57 +85,7 @@
 	src/mesa/program/lex.yy.c			\
 	src/mesa/program/program_parse.tab.c		\
 	src/mesa/program/program_parse.tab.h		\
-	src/gallium/drivers/r600/Makefile.in		\
-	src/gallium/drivers/r300/Makefile.in		\
-	src/gallium/drivers/Makefile.in			\
-	src/gallium/Makefile.in				\
-	src/gallium/auxiliary/pipe-loader/Makefile.in	\
-	src/gallium/targets/opencl/Makefile.in		\
-	src/gallium/state_trackers/clover/Makefile.in	\
-	src/mapi/glapi/tests/Makefile.in		\
-	src/mapi/glapi/Makefile.in			\
-	src/mapi/glapi/gen/Makefile.in			\
-	src/mapi/es1api/Makefile.in			\
-	src/mapi/shared-glapi/tests/Makefile.in		\
-	src/mapi/shared-glapi/Makefile.in		\
-	src/mapi/vgapi/Makefile.in			\
-	src/mapi/es2api/Makefile.in			\
-	src/glsl/tests/Makefile.in			\
-	src/glsl/glcpp/Makefile.in			\
-	src/glsl/builtin_compiler/Makefile.in		\
-	src/glsl/Makefile.in				\
-	src/gtest/Makefile.in				\
-	src/egl/drivers/Makefile.in			\
-	src/egl/drivers/glx/Makefile.in			\
-	src/egl/drivers/dri2/Makefile.in		\
-	src/egl/Makefile.in				\
-	src/egl/main/Makefile.in			\
-	src/egl/wayland/Makefile.in			\
-	src/egl/wayland/wayland-drm/Makefile.in		\
-	src/egl/wayland/wayland-egl/Makefile.in		\
-	src/Makefile.in					\
-	src/glx/tests/Makefile.in			\
-	src/glx/Makefile.in				\
-	src/gbm/Makefile.in				\
-	src/mesa/drivers/Makefile.in			\
-	src/mesa/drivers/dri/common/Makefile.in		\
-	src/mesa/drivers/dri/i965/Makefile.in		\
-	src/mesa/drivers/dri/r200/Makefile.in		\
-	src/mesa/drivers/dri/Makefile.in		\
-	src/mesa/drivers/dri/radeon/Makefile.in		\
-	src/mesa/drivers/dri/swrast/Makefile.in		\
-	src/mesa/drivers/dri/nouveau/Makefile.in	\
-	src/mesa/drivers/dri/i915/Makefile.in		\
-	src/mesa/drivers/osmesa/Makefile.in		\
-	src/mesa/drivers/x11/Makefile.in		\
-	src/mesa/Makefile.in				\
-	src/mesa/libdricore/Makefile.in			\
-	src/mesa/x86-64/Makefile.in			\
-	src/mesa/program/Makefile.in			\
-	src/mesa/main/tests/Makefile.in			\
-	src/mesa/main/tests/hash_table/Makefile.in	\
-	src/mesa/x86/Makefile.in			\
-	Makefile.in
+	`git ls-files | grep "Makefile.am" | sed -e "s/Makefile.am/Makefile.in/"`
 
 
 IGNORE_FILES = \