fix VS compile error

sokol_gfx.h

@@ -6016,7 +6016,7 @@ _SOKOL_PRIVATE sg_resource_state _sg_create_pipeline(_sg_pipeline_t* pip, _sg_sh
     bs_desc.RenderTarget[0].SrcBlendAlpha = _sg_d3d11_blend_factor(desc->blend.src_factor_alpha);
     bs_desc.RenderTarget[0].DestBlendAlpha = _sg_d3d11_blend_factor(desc->blend.dst_factor_alpha);
     bs_desc.RenderTarget[0].BlendOpAlpha = _sg_d3d11_blend_op(desc->blend.op_alpha);
-    bs_desc.RenderTarget[0].RenderTargetWriteMask = _sg_d3d11_color_write_mask(desc->blend.color_write_mask);
+    bs_desc.RenderTarget[0].RenderTargetWriteMask = _sg_d3d11_color_write_mask((sg_color_mask)desc->blend.color_write_mask);
     hr = ID3D11Device_CreateBlendState(_sg.d3d11.dev, &bs_desc, &pip->d3d11_bs);
     SOKOL_ASSERT(SUCCEEDED(hr) && pip->d3d11_bs);