Patches for tic54x target (includes TI COFF support)

[Timothy Wall]

These patches (and new files) implement support for the TI c54x
processor.  Included is support for targets with bytes that are not
necessarily 8 bits wide, and support for TI's flavor of COFF.

I'd like some input on the octets vs bytes issue, which Ian has some
valid concerns about.  These patches elucidate many of the ambiguous
uses of host octets vs target bytes (which in this case are 16 bits, not
8 bits), but probably not all.  I've modified those places that are
actually used by most targets which care about non-octet target bytes.
Forcing all targets to pay attention is overkill, and I think I've hit
all the general code.  What is missing is a general guide for how to
implement new "general" code so that it doesn't break targets that
depend on non-octet bytes.

The new tic54x files I'll post separately, since the test suite is
rather large.

Tim Wall
twall at cygnus dot com