add missing shared lib visibility macros

fixes linker errors when using is_component_build

Change-Id: Ie28b0e8881cb81715a959df3a87bae4fa854afda
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/206140
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Auto-Submit: Martin Vejdarski <martin@mainframe.co.uk>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
3 files changed