SkPDF: set SK_SFNTLY_SUBSETTER uniformly

When Skia is built into the Android framework,
SK_SFNTLY_SUBSETTER="sample/chromium/font_subsetter.h".
This #includes the same value for GOOGLE3.

Once Chrome is also using this value, we can do away with
the `#ifdef GOOGLE3` line.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2272103002

Review-Url: https://codereview.chromium.org/2272103002
1 file changed