buildgcc: Fix wrapper Makefile

buildgcc moved from building gdb by default (with opt-out) to
gdb being optional. Adapt Makefile so it works again

Change-Id: I663a8c70db4f7b5d07456fb67a223dbb2de2c133
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/417
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

util/crossgcc/Makefile

@@ -1,11 +1,11 @@
 all: build
 
 build:
-	bash ./buildgcc
+	bash ./buildgcc -G
 
 .PHONY: build-without-gdb
 build-without-gdb:
-	bash ./buildgcc --skip-gdb
+	bash ./buildgcc
 
 clean:
 	rm -rf xgcc