add API to change max pointsize for font cache

Bug: skia:6585
Change-Id: I6df8c439dca0a154e8fbfce6d66c536665dff1d7
Reviewed-on: https://skia-review.googlesource.com/18314
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
5 files changed