st/wgl: set PIPE_BIND_SAMPLER_VIEW for window color buffers
st/wgl: set PIPE_BIND_SAMPLER_VIEW for window color buffers

To allow sampling from the surface for things like glCopyPixels
or glCopyTexSubImage.

Reviewed-by: Charmaine Lee <67ce69700661ea856134ddb10419a330e5f037d7@vmware.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler