Fixed resource leak and crash at exit in the D3D11 renderer

Also, for some reason ID3D11DeviceContext_OMGetRenderTargets() was failing in the second read pixels call in the "testautomation --filter render_testViewport" test.

We already know the target view, so just use that.

(cherry picked from commit 619f65af0c390dd10bc0e6bf9dc1227e7ecee54d)

src/render/direct3d11/SDL_render_d3d11.c

@@ -2143,7 +2143,7 @@ static int D3D11_RenderReadPixels(SDL_Renderer *renderer, const SDL_Rect *rect,
     D3D11_BOX srcBox;
     D3D11_MAPPED_SUBRESOURCE textureMemory;
 
-    ID3D11DeviceContext_OMGetRenderTargets(data->d3dContext, 1, &renderTargetView, NULL);
+    renderTargetView = D3D11_GetCurrentRenderTargetView(renderer);
     if (renderTargetView == NULL) {
         SDL_SetError("%s, ID3D11DeviceContext::OMGetRenderTargets failed", __FUNCTION__);
         goto done;