set externals/gyp dependency to same version as manually imported gyp code

git-svn-id: http://skia.googlecode.com/svn/trunk@1571 2bbb7eff-a529-9590-31e7-b0007b416f81

DEPS

@@ -7,5 +7,5 @@
 
 use_relative_paths = True
 deps = {
-  "third_party/externals/gyp" : "http://gyp.googlecode.com/svn/trunk@930",
+  "third_party/externals/gyp" : "http://gyp.googlecode.com/svn/trunk@907",
 }

third_party/gyp/README.skia

-This is a snap of GYP (http://code.google.com/p/gyp/) at r197
+This is a snap of GYP (http://code.google.com/p/gyp/) at r907,
+added by bsalomon on 30 March 2011.
+
+(Brian had originally recorded that this was a snap as of r197,
+but the gyp code copied over is very different than r197;
+further investigation indicates that it was probably r907.)
 
 svn export http://gyp.googlecode.com/svn/trunk/