Rename some "aux" functions.

Rename some "aux" functions.

"aux" doesn't contribute anything to the name, and it makes the
reader wonder what it's supposed to mean.

gdb/ChangeLog:

	* symtab.c (lookup_local_symbol): Renamed from lookup_symbol_aux_local.
	All callers updated.
	(lookup_symbol_in_all_objfiles): Renamed from
	lookup_symbol_aux_symtabs.  All callers updated.
	(lookup_symbol_via_quick_fns): Renamed from lookup_symbol_aux_quick.
	All callers updated.
	(lookup_symbol_in_objfile_symtabs): Renamed from
	lookup_symbol_aux_objfile.  All callers updated.