fix(cros-workon.eclass): Do not add -clang to CFLAGS

Not sure how this managed to work in the past, perhaps the test for
using Google's common.mk used to always fail but now works properly?
In any case, we don't use clang any more.

sdk_container/src/third_party/coreos-overlay/eclass/cros-workon.eclass

@@ -503,13 +503,6 @@ cros-workon_src_configure() {
 	else
 		default
 	fi
-	local p
-	for p in "${CROS_WORKON_PROJECT[@]}"; do
-		if [[ ${p} == chromiumos/platform/* ]]; then
-			append-flags -clang
-			break
-		fi
-	done
 }
 
 cw_emake() {