Roll GYP for Windows 10 project generation.

BUG=angleproject:1122

Change-Id: I8b7a33fb8e7d1200e655c73c7d1a5502cac955c6
Reviewed-on: https://chromium-review.googlesource.com/293335
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Cooper Partin <coopp@microsoft.com>
Commit-Queue: Cooper Partin <coopp@microsoft.com>

DEPS

@@ -4,7 +4,7 @@ vars = {
 
 deps = {
   "third_party/gyp":
-      Var('chromium_git') + "/external/gyp@b4781fc38236b0fb1238969c918a75a200cfffdb",
+      Var('chromium_git') + "/external/gyp@81c2e5ff92af29bab61c982808076ddce3d200a2",
 
   # TODO(kbr): figure out how to better stay in sync with Chromium's
   # versions of googletest and googlemock.