Add missing SK_API exports in SkMesh.h

Export SkMesh and SkMeshSpecification.

Change-Id: Ie90868cf9f804a762f04bca4d249d1fdeca3d114
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/806976
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Lei Zhang <thestig@chromium.org>
1 file changed