Make public.bzl declare BMP and WBMP support

A partner CL to http://review.skia.org/811816, this will allow
us to properly guard code as we migrate onto the buffet build.

Bug: b/40045064
Change-Id: I1affa183885bf769c9c908097d38227e2eeafc65
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/811818
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
1 file changed