x86: enable FORTIFY_SOURCE

Enable FORTIFY_SOURCE for Android x86.  This adds certain security
protections to Android programs, checking for common programming
mistakes and buffer overflows.

FORTIFY_SOURCE protections have been enabled for ARM since
a46c480e43cc61d0190569684f0a1e53a5da75b6 (Jun 4th 2012)

Change-Id: Idae6f93d37ddae605088867cd3029f12632456e1
diff --git a/core/combo/TARGET_linux-x86.mk b/core/combo/TARGET_linux-x86.mk
index 569914b..948ee17 100644
--- a/core/combo/TARGET_linux-x86.mk
+++ b/core/combo/TARGET_linux-x86.mk
@@ -84,6 +84,7 @@
 			-Ulinux \
 			-Wa,--noexecstack \
 			-Werror=format-security \
+			-D_FORTIFY_SOURCE=1 \
 			-Wstrict-aliasing=2 \
 			-fPIC -fPIE \
 			-ffunction-sections \