Remove parameter from end_psymtab_common

Remove parameter from end_psymtab_common

The objfile parameter to end_psymtab_common is no longer needed, so
this removes it.

gdb/ChangeLog
2020-11-01  Tom Tromey  <tom@tromey.com>

	* dbxread.c (dbx_end_psymtab): Update.
	* dwarf2/read.c (process_psymtab_comp_unit_reader): Update.
	(build_type_psymtabs_reader): Update.
	* xcoffread.c (xcoff_end_psymtab): Update.
	* ctfread.c (scan_partial_symbols): Update.
	* psympriv.h (end_psymtab_common): Update.
	* psymtab.c (end_psymtab_common): Remove objfile parameter.
	(sort_pst_symbols): Likewise.