[patch] config.gcc: Obsolete c4x.

[Kazu Hirata]

Hi Mark,

> Kazu, let's make Ralf and Joel happy, and make this a somewhat more 
> gentle transition.  Would you please add the bits back to the 4.0 
> branch?  At the same time, add c4x to the list of obsolete targets, so 
> that --enable-obsolete is required to actually build it.  Let's leave 
> the mainline alone; if someone actually does come forward to maintain 
> the port, we can resurrect it.

All I have done so far is touch --enable-obsolete.  I have not removed
any file.

c4x has been added to the list of obsolete targets on the web site as
well as config.gcc on both 4.0 branch (but not 4.0.0) and mainline.

Should I remove the config.gcc bits on mainline?  I think
--enable-obsolete is a fairly low hurdle, but if you think otherwise,
I'm going to not require --enable-obsolete for c4x on mainline.

Kazu Hirata