minor bug in objc-load.m: objc_load_module

[Michael Scheibler]

_objc_load_load_callback = loadCallback;
_objc_load_callback = objc_load_callback;
.
.
.
handle = __objc_dynamic_link(filename, 1, debugFilename);
if (handle == 0) {
 if (errorStream)
  __objc_dynamic_error(errorStream, "Error (objc-load)");
 return 1;  // _objc_load_callback is not reset!!
}
.
. // more "return 1"s coming
.
_objc_load_callback = 0; // only if successful
_objc_load_load_callback = 0;