[RFA]: Remove unused header files.

[Andrew Cagney]

J.T.

GDB currently has some really obscure and effectivly hidden include
dependencies.  For instance, given the target mn10200-elf you find:

	values.c uses EXTRACT_RETURN_VALUE

	config/mn10200/tm-mn10200.h's definition
		refers to something declared in regcache.h

	values.c includes "tm.h" to get at EXTRACT_RETURN_VALUE and
consequently needs a declaration for regcache.h.

Does your lint handle this?

	Andrew