(objc_verror): New function.

(objc_verror): New function.

(objc_fatal): Remove function.
(objc_set_error_handler): New function.
(_objc_error_handler): New global variable.
(__alpha__): Remove unneeded code.
(objc_error): Allow user specified error handler function to trap and
handle the objc error.  Added an error code parameter which indicates
the specific error that occured.
(objc_malloc, objc_atomic_malloc): Replace call to objc_fatal function
with call to objc_error function.
(objc_valloc, objc_realloc, objc_calloc): Likewise.

From-SVN: r13589