[Pixman] Eliminate composite methods

[Soeren Sandmann]

Hi,

The next step in the flags series is this branch:

        http://cgit.freedesktop.org/~sandmann/pixman/log/?h=eliminate-composite

which eliminates all the composite methods in favor of a direct search
of all the fast path tables. To make this work, the general path is
now also considered a fast path, so that the search is guaranteed to
find something that will work.

Comments appreciated.

Thanks,
Soren