SkTHash: hash from fnptr to functor type

SkTHash: hash from fnptr to functor type

Passing &SkGoodHash to SkTHashMap and SkTHashSet doesn't guarantee that it's actually instantiated.  Using a functor does.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/c8d1dd48c01f562cfffe64da0e5cee5ed2713541

[mtklein_C, 2015-10-15 18:36:46]

The CQ bit was checked by mtklein@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-10-15 18:36:59]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1405053002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1405053002/1

[mtklein_C, 2015-10-15 18:40:18]

mtklein@chromium.org changed reviewers:
+ bungeman@google.com

[commit-bot: I haz the power, 2015-10-15 18:46:02]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-10-15 18:46:03]

Dry run: This issue passed the CQ dry run.

[bungeman-skia, 2015-10-15 19:18:49]

lgtm

[mtklein, 2015-10-15 19:22:13]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-10-15 19:22:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1405053002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1405053002/1

[commit-bot: I haz the power, 2015-10-15 19:23:05]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/c8d1dd48c01f562cfffe64da0e5cee5ed2713541