[rfa] make clean should remove observe.h and observer.inc

[Michael Snyder]

Joel Brobecker wrote:
>> That brings up another question.  What about <lang>-exp.c?  Technically
>> they are generated files.  Should make clean remove them?
> 
> I would say no - we check them in so to allow users to build
> GDB without requiring bison/flex. It would be problematic for
> them if they disappeared at a simple "make clean".
> 

We don't check them in -- they're not in cvs.  We add them to the tar 
file when we make a release.

OK, though, how about "make distclean"?