Add NaCl OS ABI to enumeration.

gdb/osabi.c

 /* OS ABI variant handling for GDB.
 
    Copyright (C) 2001-2004, 2007-2012 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.
@@ skipping 54 matching lines @@
   "Irix",
   "Interix",
   "HP/UX ELF",
   "HP/UX SOM",
   "QNX Neutrino",
   "Cygwin",
   "AIX",
   "DICOS",
   "Darwin",
   "Symbian",
+  "NaCl",
 
   "<invalid>"
 };
 
 const char *
 gdbarch_osabi_name (enum gdb_osabi osabi)
 {
   if (osabi >= GDB_OSABI_UNKNOWN && osabi < GDB_OSABI_INVALID)
     return gdb_osabi_names[osabi];
 
@@ skipping 560 matching lines @@
 
   /* Register the "set osabi" command.  */
   add_setshow_enum_cmd ("osabi", class_support, gdb_osabi_available_names,
                         &set_osabi_string,
                         _("Set OS ABI of target."),
                         _("Show OS ABI of target."),
                         NULL, set_osabi, show_osabi,
                         &setlist, &showlist);
   user_osabi_state = osabi_auto;
 }