MFC r288071:

- arm64 change was omitted due to lack of architecture support
- ia64 change was added as the architecture was removed from ^/head

Sponsored by: EMC / Isilon Storage Division

r288071 (by emaste):

Move kbd.c to main sys/conf/files list

It is (optionally) used on all architectures.

MFC r261891: provide fast versions of ffsl and flsl for i386; ffsll and
flsll for amd64

MFC r263323: Fix and improve exception tracing.

MFC r263323: Fix and improve exception tracing.