Revert "Revert "Turn on _FORTIFY_SOURCE=2 for the host.""

This reverts commit e27b214fc248d8927c42c5529d5c9fe75e2591aa.

Change-Id: I3d739c0594dbe4ecd62c5b07064ada7de6cdaadb
diff --git a/core/combo/HOST_linux-x86.mk b/core/combo/HOST_linux-x86.mk
index 8eda6c0..3acf795 100644
--- a/core/combo/HOST_linux-x86.mk
+++ b/core/combo/HOST_linux-x86.mk
@@ -40,8 +40,7 @@
   -no-canonical-prefixes \
   -include $(call select-android-config-h,linux-x86)
 
-# TODO: Set _FORTIFY_SOURCE=2. Bug 20558757.
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=0 -fstack-protector
+$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fstack-protector
 
 # Workaround differences in inttypes.h between host and target.
 # See bug 12708004.
diff --git a/core/combo/HOST_linux-x86_64.mk b/core/combo/HOST_linux-x86_64.mk
index e268e41..b74990b 100644
--- a/core/combo/HOST_linux-x86_64.mk
+++ b/core/combo/HOST_linux-x86_64.mk
@@ -40,8 +40,7 @@
   -no-canonical-prefixes \
   -include $(call select-android-config-h,linux-x86)
 
-# TODO: Set _FORTIFY_SOURCE=2. Bug 20558757.
-HOST_GLOBAL_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=0 -fstack-protector
+HOST_GLOBAL_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fstack-protector
 
 # Workaround differences in inttypes.h between host and target.
 # See bug 12708004.