Bump pessimizing-move from -Wno to -Wno-error

This is a useful warning that can point out lower performance code.

https://r.android.com/q/hashtag:pessimizing-move-cleanup cleaned up many
cases. Let's bump this up to a non-error warning while we fix up the
remaining cases.

The warning remains off for all external code.

Test: presubmit
Bug: 154270751
Change-Id: If6b69cbaa1384e81336b6842607a587bf6c7f38b

cc/config/global.go

@@ -275,7 +275,7 @@ var (
 		"-Wno-zero-as-null-pointer-constant",        // http://b/68236239
 		"-Wno-deprecated-anon-enum-enum-conversion", // http://b/153746485
 		"-Wno-deprecated-enum-enum-conversion",
-		"-Wno-pessimizing-move", // http://b/154270751
+		"-Wno-error=pessimizing-move", // http://b/154270751
 		// New warnings to be fixed after clang-r399163
 		"-Wno-non-c-typedef-for-linkage", // http://b/161304145
 		// New warnings to be fixed after clang-r428724
@@ -368,6 +368,7 @@ var (
 		"-Wno-unqualified-std-cast-call",
 		"-Wno-array-parameter",
 		"-Wno-gnu-offsetof-extensions",
+		"-Wno-pessimizing-move",
 		// TODO: Enable this warning http://b/315245071
 		"-Wno-fortify-source",
 	}