Turn on stack protector for mips64.

Go straight to -fstack-protector-strong, since it works to boot the emulator.

Change-Id: I2b65a0ab4426856ae05f66c1e294951e45bd72b6
diff --git a/core/combo/TARGET_linux-mips64.mk b/core/combo/TARGET_linux-mips64.mk
index 9e4eaa6..3e1f61a 100644
--- a/core/combo/TARGET_linux-mips64.mk
+++ b/core/combo/TARGET_linux-mips64.mk
@@ -89,6 +89,7 @@
 			-ffunction-sections \
 			-fdata-sections \
 			-funwind-tables \
+			-fstack-protector-strong \
 			-Wa,--noexecstack \
 			-Werror=format-security \
 			-D_FORTIFY_SOURCE=2 \