Objective C features manual

[Joseph S. Myers]

At present, libobjc/objc-features.texi is a standalone manual with just
one chapter.  It has its own copy of the GFDL - slightly different from
gcc/fdl.texi, which doesn't really work well with update_web_docs since
that script presumes .texi file names are unique throughout the tree.  
The printed version doesn't have a proper title page etc..  The info
version doesn't get installed by make install.

I think this manual would make more sense moved to the gcc directory and
included as a chapter of the main GCC manual.  What do other people think?  
If it's agreed that this would be a good idea, I'll produce a patch.

-- 
Joseph S. Myers
jsm28@cam.ac.uk