automake: Convert src/mesa/drivers/Makefile to automake.
diff --git a/configure.ac b/configure.ac
index a927f7f..c702758 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2173,6 +2173,7 @@
 		src/mesa/main/tests/Makefile
 		src/mesa/x86/Makefile
 		src/mesa/x86-64/Makefile
+		src/mesa/drivers/Makefile
 		src/mesa/drivers/dri/dri.pc
 		src/mesa/drivers/dri/Makefile
 		src/mesa/drivers/dri/common/Makefile