spirv: Allow block-decorated struct types for constants
Whenever a struct type is decorated Block or BufferBlock we turn that into a GLSL_TYPE_INTERFACE. Since these decorations can end up random places, we should allow them for constants. Closes: #3252 Fixes: 9d0ae777 "spirv: Use interface type for block and buffer..." Reviewed-by:Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com> Part-of: <!5855> (cherry picked from commit 351b5137)