gyp/sfntly: set SK_SFNTLY_SUBSETTER uniformly

When Skia is built into the Android framework,
SK_SFNTLY_SUBSETTER="sample/chromium/font_subsetter.h".
This sets the same value for Skia's test framework

I will eventually move away from the
   #include PREPROCESSOR_DEFINE
trick, which does not work everywhere.

No public API changes.
TBR=reed@google.com

Review-Url: https://codereview.chromium.org/2274223002
diff --git a/gyp/sfntly.gyp b/gyp/sfntly.gyp
index 9138561..7ee7b98 100644
--- a/gyp/sfntly.gyp
+++ b/gyp/sfntly.gyp
@@ -14,9 +14,9 @@
         'sfntly_src_path': '../third_party/externals/sfntly/cpp/src',
       },
       'direct_dependent_settings': {
-        'include_dirs': [ '<(sfntly_src_path)/sample/chromium', ],
+        'include_dirs': [ '<(sfntly_src_path)', ],
         'defines': [
-          'SK_SFNTLY_SUBSETTER="font_subsetter.h"',
+          'SK_SFNTLY_SUBSETTER="sample/chromium/font_subsetter.h"',
         ],
       },
       'sources': [