Add new target: vxworks for xscale

[Richard Kenner]

    Why didn't the patch author just submit the patch to gcc-patches for
    review (whether by you, or by the VxWorks maintainers, and with possible
    comments by anyone who happened to read the patch on gcc-patches before it
    was reviewed) in the ordinary manner in the first place?

Because of the "drift" of sources: they were not against the head sources,
but against the 3.2 branch, where they could not be applied due to the state
of that branch.

What I've been working on over the last few weeks has been going
through a large list of such patches, updating them to the head sources,
reviewing and testing them, and installing them.