SkSamplingOptions ctors not explicit

Change-Id: Ifb7c153bc48020892347278048b9298efa9b982c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/704917
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
16 files changed