Build fiddle and public_headers_warnings_check only when skia_enable_tools.

This leaves libskia as the only thing we build when tools are not enabled (other GN environments like Fuchsia, Flutter, Chrome, or for people using ours and actively disabling tools).

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4993

Change-Id: I5acad66c1b068ef81c1a7e292c3524a0b1497b66
Reviewed-on: https://skia-review.googlesource.com/4993
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed