Add GYP target for sk_tool_utils.* component.

This declares a static library target in gyp/sk_tool_utils.gyp, so other
targets can depend directly on it instead of including the source file
in their source lists.

BUG=None
TEST=make all
R=mtklein@google.com

Author: tfarina@chromium.org

Review URL: https://codereview.chromium.org/348623006
diff --git a/gyp/SampleApp.gyp b/gyp/SampleApp.gyp
index 9ced81b..2bbabf9 100644
--- a/gyp/SampleApp.gyp
+++ b/gyp/SampleApp.gyp
@@ -134,9 +134,6 @@
         # Lua
         '../src/utils/SkLuaCanvas.cpp',
         '../src/utils/SkLua.cpp',
-
-        # tools
-        '../tools/sk_tool_utils.cpp',
       ],
       'sources!': [
         '../samplecode/SampleSkLayer.cpp', #relies on SkMatrix44 which doesn't compile
@@ -152,6 +149,7 @@
         'pdf.gyp:pdf',
         'skia_lib.gyp:skia_lib',
         'tools.gyp:resources',
+        'tools.gyp:sk_tool_utils',
         'views.gyp:views',
         'views_animated.gyp:views_animated',
         'xml.gyp:xml',