Revert "__imlib_LoadImage(): Additionally check loader_ret to detect loader failures"

This reverts commit a104e317ce.

Breaks image loading in certain situations.

It seems that some loaders may return 0 even when load() "succeeds".

This appears to happen with the jpeg loader when not loading data
immediately (but only reading the header).
In this case jpeg_finish_decompress() exits via _JPEGFatalErrorHandler()
-> longjmp() causing the return code to be 0.

The fix reverted here is probably basically correct, but it will have to
wait until the loaders are fixed to behave properly.

src/lib/image.c

@@ -1048,7 +1048,7 @@ __imlib_LoadImage(const char *file, ImlibProgressFunction progress,
       im->loader = best_loader;
    /* all loaders have been tried and they all failed. free the skeleton */
    /* image struct we had and return NULL */
-   if ((loader_ret == 0) || (im->w == 0))
+   if (im->w == 0)
      {
         /* if the caller wants an error return */
         if (er)