Add option to embed font data into executable.

Some tools would like to be built with all resources embedded.
This change makes it possible to build a font manager which
uses font data embedded into the executable.

Review URL: https://codereview.chromium.org/1015723004
diff --git a/gyp/common_variables.gypi b/gyp/common_variables.gypi
index 1b9cf33..80ab7c9 100644
--- a/gyp/common_variables.gypi
+++ b/gyp/common_variables.gypi
@@ -122,6 +122,7 @@
       #     SkFontHost_fontconfig interface; use the SkFontHost_linux
       #     version instead.
       'skia_no_fontconfig%': '0',
+      'skia_embedded_fonts%': '0',
 
       'skia_sanitizer%': '',
       'skia_scalar%': 'float',
@@ -200,6 +201,7 @@
 
     'skia_freetype_static%': '<(skia_freetype_static)',
     'skia_no_fontconfig%': '<(skia_no_fontconfig)',
+    'skia_embedded_fonts%': '<(skia_embedded_fonts)',
     'skia_sanitizer%': '<(skia_sanitizer)',
     'skia_scalar%': '<(skia_scalar)',
     'skia_mesa%': '<(skia_mesa)',