More replace reg_name[] with REGISTER_NAME().
* gnu-nat.c, gnu-nat.h, msg.defs, exc_request.defs, i386gnu-nat.c, msg_reply.defs, notify.defs, process_reply.defs, reply_mig_hack.awk, config/nm-gnu.h, config/i386/{i386gnu.mh, i386gnu.mt, nm-gnu.h, m-i386gnu.h, xm-i386gnu.h}: New files for GNU hurd.