Ubuntu 12.04 error: "_FORTIFY_SOURCE" redefined [-Werror]

http://blog.sina.com.cn/s/blog_643e838601015ngx.html

from external/mesa3d/src/glsl/loop_analysis.h:29,
<command-line>:0:0: error: "_FORTIFY_SOURCE" redefined [-Werror]
 <built-in>:0:0: note: this is the location of the previous definition
 cc1plus: all warnings being treated as errors
make: *** [out/host/linux-x86/obj/EXECUTABLES/obbtool_intermediates/Main.o] Error 1

解决方法：
修改源码目录下/build/core/combo/HOST_linux-x86.mk文件：
将以下语句
HOST_GLOBAL_CFLAGS += -D_FORTIFY_SOURCE=0
修改为
HOST_GLOBAL_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=0

ATTENTION:
There is a SPACE between the -U_FORTIFY_SOURCE and -D_FORTIFY_SOURCE