Fix broken scan-build

Adding support for the multiple architectures broke the scan-build
option.  The new CC setting needed to be wrapped and not run again
when doing the scan-build second pass.

Change-Id: Ieb418f51d44803308040926a4154fb5fdc3ba67f
Signed-off-by: Martin Roth <martin@se-eng.com>
Reviewed-on: http://review.coreboot.org/2031
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

Makefile

@@ -123,7 +123,9 @@ ARCH-y := $(ARCHDIR-y)
 ARCH-$(CONFIG_ARCH_ARMV7)   := armv7
 ARCH-$(CONFIG_ARCH_X86)     := i386
 
+ifneq ($(INNER_SCANBUILD),y)
 CC := $(CC_$(ARCH-y))
+endif
 AS := $(AS_$(ARCH-y))
 LD := $(LD_$(ARCH-y))
 NM := $(NM_$(ARCH-y))