Mir: Replaced memcpy() with SDL_memcpy().

src/video/mir/SDL_mirframebuffer.c

@@ -132,7 +132,7 @@ MIR_UpdateWindowFramebuffer(_THIS, SDL_Window* window,
 
         bytes_per_row =  bytes_per_pixel * w;
         for (j = 0; j < h; j++) {
-            memcpy(s_dest, pixels, bytes_per_row);
+            SDL_memcpy(s_dest, pixels, bytes_per_row);
             pixels += s_stride;
             s_dest += d_stride;
         }

src/video/mir/SDL_mirmouse.c

@@ -93,7 +93,7 @@ CopySurfacePixelsToMirStream(SDL_Surface* surface, MirBufferStream* stream)
 
     for (i = 0; i < s_h; i++)
     {
-        memcpy(dest, pixels, bytes_per_row);
+        SDL_memcpy(dest, pixels, bytes_per_row);
         dest   += r_stride;
         pixels += p_stride;
     }