Enable -Wsizeof-array-div for 3P code.

This warning usually indicates an incorrect size being computed,
which can cause severe bugs.

Bug: 296422292
Test: presubmit
Change-Id: I381dea70a6a408883ec772ccc006746ad66b835f
diff --git a/cc/config/global.go b/cc/config/global.go
index 23a05be..5fbb311 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -251,9 +251,6 @@
 	noOverrideExternalGlobalCflags = []string{
 		// http://b/191699019
 		"-Wno-format-insufficient-args",
-		// http://b/296422292
-		// Usually signals a mistake and should be a hard error.
-		"-Wno-sizeof-array-div",
 		// http://b/296321145
 		// Indicates potential memory or stack corruption, so should be changed
 		// to a hard error. Currently triggered by some vendor code.