rmodule: add rmodules class and new type

Add an rmodules class so that there are default rules for compiling
files that will be linked by the rmodule linker. Also, add a new type
for SIPI vectors.

Change-Id: Ided9e15577b34aff34dc23e5e16791c607caf399
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2751
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
diff --git a/Makefile.inc b/Makefile.inc
index 3fb74e7..da350d1 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -60,7 +60,7 @@
 
 #######################################################################
 # Add source classes and their build options
-classes-y := ramstage romstage bootblock smm smmstub cpu_microcode
+classes-y := ramstage romstage bootblock smm smmstub cpu_microcode rmodules
 
 #######################################################################
 # Helper functions for ramstage postprocess