For the record.  The software letter for this patch has been completed. 
  This making it possible for GDB developers to examine the actual changes.

 From a quick exmination:

- the patch is against a very old code base [20021129], the actual 
changes will most likely no longer be applicable.  GDB's frame, register 
and inferior-function-call code have, for instance, all been overhauled

- changes such as:
+void
+_initialize_ppc64_linux_tdep (void)
+{
+  /* hardware/kernel supports single stepping */
+  set_gdbarch_software_single_step (current_gdbarch, NULL);
+}
and:
+#if defined (SOLIB_BREAK_NAME)
+#ifdef DROP_TEXT_NAME_PREFIX_CHAR
+#ifdef SKIP_DATA_IN_OPD
+#undef SKIP_TRAMPOLINE_CODE
+#ifdef DEAD_CODE
are simply wrong wrong.  With one exception related to shared libraries, 
GDB only accepts strict multi-arch targets.

Someone has a lot of work ahead of them, sigh.

Andrew