Add a dry-run option to gyp_skia.

gyp_skia

Index: gyp_skia
===================================================================
--- gyp_skia	(revision 14665)
+++ gyp_skia	(working copy)
@@ -129,5 +129,9 @@
   print 'Updating projects from gyp files...'
   sys.stdout.flush()
 
-  # Off we go...
-  sys.exit(gyp.main(args))
+  if '--dry-run' in args:
+    args.remove('--dry-run')
+    print gyp_source_dir, ' '.join(args)
+  else:
+    # Off we go...
+    sys.exit(gyp.main(args))