Remove parameter names from libiberty.h

[DJ Delorie]

Opinions follow...

Since libiberty has a separate texinfo documentation that's supposed
to document all the parameters, and since most of libiberty's
functions are common system functions anyway, IMHO it's not as big a
deal if libiberty.h doesn't have names of parameters in it.

In DJGPP we got around this by adding underscores, but that was
acceptable only because it was the C library and that namespace was
reserved for it.

Commented out parameter names gets messy fast, esp for functions with
lots of parameters.