PING: allow match_test to be used for attribute rtxes

[Richard Sandiford]

Ping for:

    http://gcc.gnu.org/ml/gcc-patches/2011-08/msg01181.html
    http://gcc.gnu.org/ml/gcc-patches/2011-08/msg01182.html

which allow attributes to use (match_test ...) instead of
(ne (symbol_ref ..) (const_int 0)).

Uros has already approved the x86 part (thanks).

Richard