Make SkPathMeasure move-able

Both SkPathMeasure and SkContourMeasureIter have default constructors
that put the object in a well-defined (but useless) state. Moving their
internals will restore them to this state, so there's no reason not to
have this functionality.

Change-Id: I5ce4ccd8228bc0e59092af12f359a56aeb49d2d3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/712836
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Herb Derby <herb@google.com>
4 files changed