Remake SkStrikeCache::commonSetup as constructor.

Also explicitly default all special methods of SkStrikeCache to get
nicer warnings.

Change-Id: I8856a905c6075ca52d4ad900ccd0dacc581cd485
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/350637
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Herb Derby <herb@google.com>
3 files changed