NMIs now come from 'nmi_calltrap' rather than 'calltrap', so teach 'kgdb'

to treat the frame under 'nmi_calltrap' as a trapframe.

MFC after:	3 days
Approved by:	re (bmah)

gnu/usr.bin/gdb/kgdb/trgt_amd64.c

@@ -178,6 +178,7 @@ kgdb_trgt_trapframe_sniffer(struct frame_info *next_frame)
 	if (pname == NULL)
 		return (NULL);
 	if (strcmp(pname, "calltrap") == 0 ||
+	    strcmp(pname, "nmi_calltrap") == 0 ||
 	    (pname[0] == 'X' && pname[1] != '_'))
 		return (&kgdb_trgt_trapframe_unwind);
 	/* printf("%s: %lx =%s\n", __func__, pc, pname); */