Revert^6 "Move -Wno-enum-compare{,-switch} to external cflags"

This reverts commit c729b508c309cfce45349e62ec11acb8f8d934a9.

Reason for revert: New breakages fixed

Change-Id: I8b5e597fdb2af782d591ddcf5b4e7534273a2e7b
Merged-In: I8b5e597fdb2af782d591ddcf5b4e7534273a2e7b
diff --git a/cc/config/clang.go b/cc/config/clang.go
index 22e428f..36afc68 100644
--- a/cc/config/clang.go
+++ b/cc/config/clang.go
@@ -173,19 +173,16 @@
 		// this new warning are fixed.
 		"-Wno-null-pointer-arithmetic",
 
-		// http://b/72330874 Disable -Wenum-compare until the instances detected by this new
-		// warning are fixed.
-		"-Wno-enum-compare",
-		"-Wno-enum-compare-switch",
-
 		// Disable c++98-specific warning since Android is not concerned with C++98
 		// compatibility.
 		"-Wno-c++98-compat-extra-semi",
 	}, " "))
 
-	// Extra cflags for projects under external/ directory
+	// Extra cflags for projects under external/ directory to disable warnings that are infeasible
+	// to fix in all the external projects and their upstream repos.
 	pctx.StaticVariable("ClangExtraExternalCflags", strings.Join([]string{
-		// TODO(yikong): Move -Wno flags here
+		"-Wno-enum-compare",
+		"-Wno-enum-compare-switch",
 	}, " "))
 }