Ping^2: PR target/45074: Check targets of multi-word operations

[Richard Sandiford]

Ping for:

    http://gcc.gnu.org/ml/gcc-patches/2011-04/msg01327.html

It fixes the expansion of multiword operations in cases where the
suggested target is a hard register and where CANNOT_CHANGE_MODE_CLASS
forbids word-mode subparts.

Richard