Add "objfile" parameter to two partial_symtab methods

Add "objfile" parameter to two partial_symtab methods

This series will cause partial symtabs to be shared across objfiles.
However, full symtabs and symbols will still be objfile-dependent, so
will be expanded separately for each objfile.  So, a debug info reader
will need to know which objfile to consult when expanding a partial
symtab.

This patch adds an objfile parameter to the two relevant methods of
partial_symtab.  Current implementations simply ignore them.

gdb/ChangeLog:

	* psymtab.c (partial_map_expand_apply)
	(psym_find_pc_sect_compunit_symtab, psym_lookup_symbol)
	(psym_lookup_global_symbol_language)
	(psymtab_to_symtab, psym_find_last_source_symtab, dump_psymtab)
	(psym_print_stats, psym_expand_symtabs_for_function)
	(psym_map_symbol_filenames, psym_map_matching_symbols)
	(psym_expand_symtabs_matching)
	(partial_symtab::read_dependencies, maintenance_info_psymtabs)
	(maintenance_check_psymtabs): Update.
	* psympriv.h (struct partial_symtab) <readin_p,
	get_compunit_symtab>: Add objfile parameter.
	(struct standard_psymtab) <readin_p, get_compunit_symtab>:
	Likewise.
	* dwarf2/read.c (struct dwarf2_include_psymtab) <readin_p,
	get_compunit_symtab>: Likewise.
	(dwarf2_psymtab::expand_psymtab): Pass objfile argument.

Change-Id: I3f0b26787c3e78f7fb78b9fc011d91fb8690f3a0