Move SkFontConfigInterface to smart pointers.

This old interface may be easier to move away from if it isn't so
difficult to understand.

Change-Id: Ib04b00e55fd5c11aca8cc70bc6c7b0b5ba98dcae
Reviewed-on: https://skia-review.googlesource.com/127969
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
2 files changed