Add firmware build mode to Makefiles

Makefile

 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+export FIRMWARE_ARCH
+
 export CC ?= gcc
 export CXX ?= g++
+ifeq ($(FIRMWARE_ARCH),)
 export CFLAGS = -Wall -Werror -DCHROMEOS_ENVIRONMENT
+else
+export CFLAGS = -Wall -Werror
+endif
+
 ifeq (${DEBUG},)
 CFLAGS += -O3
 else
 CFLAGS += -O0 -g -DVBOOT_DEBUG
 endif
+
 ifeq (${DISABLE_NDEBUG},)
 CFLAGS += -DNDEBUG
 endif
 
 export TOP = $(shell pwd)
 export FWDIR=$(TOP)/firmware
 export HOSTDIR=$(TOP)/host
+ifeq ($(FIRMWARE_ARCH),)
 export INCLUDES = -I$(FWDIR)/include -I$(FWDIR)/stub/include
+else
+export INCLUDES = -I$(FWDIR)/include -I$(FWDIR)/arch/$(FIRMWARE_ARCH)/include
+endif
 
 export BUILD = ${TOP}/build
 export FWLIB = ${BUILD}/vboot_fw.a
 export HOSTLIB = ${BUILD}/vboot_host.a
 
+ifeq ($(FIRMWARE_ARCH),)
 SUBDIRS = firmware host utility cgpt tests tests/tpm_lite
+else
+SUBDIRS = firmware
+endif
 
 all:
         set -e; \
         for d in $(shell find ${SUBDIRS} -name '*.c' -exec  dirname {} \; |\
                  sort -u); do \
                 newdir=${BUILD}/$$d; \
                 if [ ! -d $$newdir ]; then \
                         mkdir -p $$newdir; \
                 fi; \
         done; \
-        make -C utility update_tlcl_structures; \
+        [ -z "$(FIRMWARE_ARCH)" ] && make -C utility update_tlcl_structures; \
         for i in $(SUBDIRS); do \
                 make -C $$i; \
         done
 
 clean:
         /bin/rm -rf ${BUILD}
 
 install:
         $(MAKE) -C utility install
         $(MAKE) -C cgpt install
 
 runtests:
         $(MAKE) -C tests runtests
 
 rbtest:
         $(MAKE) -C tests rbtest