Fix Compiler::get_decoration to correctly return > 0 if DecorationNonWritable or DecorationNonReadable are specified.
Fix Compiler::get_decoration to correctly return > 0 if DecorationNonWritable or DecorationNonReadable are specified.

KhronosGroup/SPIRV-Cross,KhronosGroup/SPIRV-Cross,KhronosGroup/SPIRV-Cross,h3xl3r/SPIRV-Cross,h3xl3r/SPIRV-Cross,KhronosGroup/SPIRV-Cross,h3xl3r/SPIRV-Cross,h3xl3r/SPIRV-Cross,h3xl3r/SPIRV-Cross,KhronosGroup/SPIRV-Cross,KhronosGroup/SPIRV-Cross