This removes the ALL_MSYMBOLS and ALL_OBJFILE_MSYMBOLS macros,
replacing their uses with ranged for loops.

In a couple of spots, a new declaration was needed in order to work
around shadowing; these are just temporary and are removed in a
subsequent patch.

gdb/ChangeLog
2019-01-09  Tom Tromey  <tom@tromey.com>

	* symtab.c (search_symbols)
	(default_collect_symbol_completion_matches_break_on): Use
	objfile_msymbols.
	* ada-lang.c (ada_lookup_simple_minsym)
	(ada_collect_symbol_completion_matches): Use objfile_msymbols.
	* minsyms.c (find_solib_trampoline_target): Use objfile_msymbols.
	* hppa-tdep.c (hppa_lookup_stub_minimal_symbol): Use
	objfile_msymbols.
	* coffread.c (coff_symfile_read): Use objfile_msymbols.
	* symmisc.c (dump_msymbols): Use objfile_msymbols.
	* objc-lang.c (find_methods): Use objfile_msymbols.
	(info_selectors_command, info_classes_command): Likewise.
	* stabsread.c (scan_file_globals): Use objfile_msymbols.
	* objfiles.h (class objfile_msymbols): New.
	(ALL_OBJFILE_MSYMBOLS): Remove.
	(ALL_MSYMBOLS): Remove.