Revert "Enable -Wfortify-source"

This reverts commit ca5e3eb407be5bd70b3cedd9a6aeb138245ec255.

Reason for revert: falcon and seahawk build failures on git_main.

Change-Id: Ib48e33dbb1649641223013739bb85934342a067a
diff --git a/cc/config/global.go b/cc/config/global.go
index d2faff2..62a4765 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -376,6 +376,8 @@
 		"-Wno-unqualified-std-cast-call",
 		"-Wno-array-parameter",
 		"-Wno-gnu-offsetof-extensions",
+		// TODO: Enable this warning http://b/315245071
+		"-Wno-fortify-source",
 	}
 
 	llvmNextExtraCommonGlobalCflags = []string{