Enable -Wfortify-source

This reverts commit 9b7e07c7aacfdeeaebcc55e46376b9a4966f9797.
Workaround for the post-submit failure in b/339523786 has been merged.

Fixes: 315245071
Change-Id: I517f13334ad169429daaa68bda7d5f600f653977
diff --git a/cc/config/global.go b/cc/config/global.go
index 16b5e09..12c1bb9 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -365,8 +365,6 @@
 		"-Wno-unqualified-std-cast-call",
 		"-Wno-array-parameter",
 		"-Wno-gnu-offsetof-extensions",
-		// TODO: Enable this warning http://b/315245071
-		"-Wno-fortify-source",
 	}
 
 	llvmNextExtraCommonGlobalCflags = []string{