Cross compile flags were missing for ar to create coreboot.a.

Signed-off-by: Marc Jones <marc.jones@amd.com>

Index: coreboot-v2/src/config/Config.lb
===================================================================
--- coreboot-v2.orig/src/config/Config.lb	2008-02-06 10:17:43.000000000 -0700
+++ coreboot-v2/src/config/Config.lb	2008-02-06 10:17:22.000000000 -0700
@@ -35,7 +35,7 @@
 makerule coreboot.a
         depends "$(OBJECTS)"
         action  "rm -f coreboot.a"
-        action  "ar cr coreboot.a $(OBJECTS)"
+        action  "$(CROSS_COMPILE) ar cr coreboot.a $(OBJECTS)"
 end
 
 
