build: Bump libcc to latest (2.0.x) (electron#13919)

poiru · MarshallOfSound · commit cf98934dd9f7 · 2018-08-03T10:54:39.000+10:00
This picks up electron/libchromiumcontent#627.
diff --git a/vendor/libchromiumcontent b/vendor/libchromiumcontent
@@ -1 +1 @@
-Subproject commit 5caba227fd37876b4813ba42c2c2ac4cf959571e
+Subproject commit 284e6d6ef2f95fd6b6d11f9af235dd541a01ff23
