radeonsi: move sid.h/r600d_common.h to a common place.

Step one to merging radv would be to move some files around.

This only adds the include path to r600/radeonsi, because later
we want to avoid having to add it to the generic target paths.

Acked-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
diff --git a/src/Makefile.am b/src/Makefile.am
index cffb9e8..91d753a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -50,6 +50,10 @@
 # include only conditionally ?
 SUBDIRS += compiler
 
+if HAVE_GALLIUM_RADEON_COMMON
+SUBDIRS += amd
+endif
+
 if HAVE_INTEL_DRIVERS
 SUBDIRS += intel
 endif