Fixes a bug in SDL_UpdateTexture when using SDL_RENDERER_SOFTWARE and texture...

Fixes a bug in SDL_UpdateTexture when using SDL_RENDERER_SOFTWARE and texture access is SDL_TEXTUREACCESS_STATIC

src/render/software/SDL_render_sw.c

@@ -240,6 +240,8 @@ SW_UpdateTexture(SDL_Renderer * renderer, SDL_Texture * texture,
     int row;
     size_t length;
 
+    if(SDL_MUSTLOCK(surface))
+        SDL_LockSurface(surface);
     src = (Uint8 *) pixels;
     dst = (Uint8 *) surface->pixels +
                         rect->y * surface->pitch +
@@ -250,6 +252,8 @@ SW_UpdateTexture(SDL_Renderer * renderer, SDL_Texture * texture,
         src += pitch;
         dst += surface->pitch;
     }
+    if(SDL_MUSTLOCK(surface))
+        SDL_UnlockSurface(surface);
     return 0;
 }