error: Don't use initGenericErrorDefaultFunc

The code in xmlInitParser did only set the error handler if it was NULL
which should never happen.

error.c

@@ -81,6 +81,8 @@ xmlGenericErrorDefaultFunc(void *ctx ATTRIBUTE_UNUSED, const char *msg, ...) {
  * initGenericErrorDefaultFunc:
  * @handler:  the handler
  *
+ * DEPRECATED: Use xmlSetGenericErrorFunc.
+ *
  * Set or reset (if NULL) the default handler for generic errors
  * to the builtin error function.
  */