Roll GYP.

Includes fixes to clean up our MSVS projects.

BUG=None

Change-Id: Ied16bf5b40e7a29ee08e76152daa1296c8960724
Reviewed-on: https://chromium-review.googlesource.com/278051
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>

DEPS

@@ -1,6 +1,6 @@
 deps = {
   "third_party/gyp":
-      "http://chromium.googlesource.com/external/gyp@9f594095c5b14f8bc518081a660e77890c294861",
+      "http://chromium.googlesource.com/external/gyp@b4781fc38236b0fb1238969c918a75a200cfffdb",
 
   # TODO(kbr): figure out how to better stay in sync with Chromium's
   # versions of googletest and googlemock.