mips:atomic.h: improve implementation of atomic ops, fix mips{el,64}
mips:atomic.h: improve implementation of atomic ops, fix mips{el,64}

The appended patch extends the configure check to cover mips64 and
mipsel, and improves the mips atomics implementation.

See http://bugs.debian.org/406409 for more detail.

Signed-off-by: LaMont Jones <0ab8dc438f73addc98d9ad5925ec8f2b97991703@debian.org>

tjaalton/bind9,tjaalton/bind9,tjaalton/bind9,tjaalton/bind9,tjaalton/bind9,tjaalton/bind9