st/mesa: Make FEATURE_feedback and FEATURE_rastpos more modular.

Make st_cb_feedback.h FEATURE_feedback aware and st_cb_rastpos.h
FEATURE_rastpos aware.  Move creation of selection/feedback draw context
to st_init_draw.

src/mesa/state_tracker/st_cb_rasterpos.h

@@ -28,6 +28,20 @@
 #ifndef ST_CB_RASTERPOS_H
 #define ST_CB_RASTERPOS_H
 
+
+#include "main/mtypes.h"
+
+#if FEATURE_rastpos
+
 extern void st_init_rasterpos_functions(struct dd_function_table *functions);
 
-#endif
+#else
+
+static INLINE void
+st_init_rasterpos_functions(struct dd_function_table *functions)
+{
+}
+
+#endif /* FEATURE_rastpos */
+
+#endif /* ST_CB_RASTERPOS_H */