create simple 'skpmaker' tool to generate SKP files for testing

gyp/tools.gyp

Index: gyp/tools.gyp
diff --git a/gyp/tools.gyp b/gyp/tools.gyp
index f748157a720155c4ff09c27cdfd9d66a2a511bc8..ce24d9db54fe2054108524da64fbae8a67ef17f3 100644
--- a/gyp/tools.gyp
+++ b/gyp/tools.gyp
@@ -13,17 +13,18 @@
       'target_name': 'tools',
       'type': 'none',
       'dependencies': [
+        'bbh_shootout',
         'bench_pictures',
         'filter',
-        'lua_pictures',
-        'bbh_shootout',
         'lua_app',
+        'lua_pictures',
         'pinspect',
         'render_pdfs',
         'render_pictures',
         'skdiff',
-        'skpdiff',
         'skhello',
+        'skpdiff',
+        'skpmaker',
         'skimage',
         'test_image_decoder',
       ],
@@ -110,6 +111,20 @@
       ],
     },
     {
+      'target_name': 'skpmaker',
+      'type': 'executable',
+      'sources': [
+        '../tools/skpmaker.cpp',
+      ],
+      'include_dirs': [
+        '../src/core',
+      ],
+      'dependencies': [
+        'flags.gyp:flags',
+        'skia_lib.gyp:skia_lib',
+      ],
+    },
+    {
       'target_name': 'skimagediff',
       'type': 'executable',
       'sources': [