Make symbol_set_names a member function

Make symbol_set_names a member function

This also renames it to make it clearer that this is not a cheap
function (to compute_and_set_names).  Also renames name to m_name
to make the implementation of the renamed function more readable.

Most of the places that access sym->m_name directly were also changed
to call linkage_name () instead, to make it clearer which name they
are accessing.

gdb/ChangeLog:

2019-12-26  Christian Biesinger  <cbiesinger@google.com>

	* ada-lang.c (ada_decode_symbol): Update.
	* buildsym.c (add_symbol_to_list): Update.
	* coffread.c (process_coff_symbol): Update.
	* ctfread.c (ctf_add_enum_member_cb): Update.
	(new_symbol): Update.
	(ctf_add_var_cb): Update.
	* dwarf2read.c (fixup_go_packaging): Update.
	(dwarf2_compute_name): Update.
	(new_symbol): Update.
	* jit.c (finalize_symtab): Update.
	* language.c (language_alloc_type_symbol): Update.
	* mdebugread.c (new_symbol): Update.
	* minsyms.c (minimal_symbol_reader::record_full): Update.
	(minimal_symbol_reader::install): Update.
	* psymtab.c (print_partial_symbols): Update.
	(psymbol_hash): Update.
	(psymbol_compare): Update.
	(add_psymbol_to_bcache): Update.
	(maintenance_check_psymtabs): Update.
	* stabsread.c (define_symbol): Update.
	* symtab.c (symbol_set_names): Rename to...
	(general_symbol_info::compute_and_set_names): ...this.
	(general_symbol_info::natural_name): Update.
	(general_symbol_info::search_name): Update.
	(fixup_section): Update.
	* symtab.h (struct general_symbol_info) <name>: Rename to...
	<m_name>: ...this.
	<compute_and_set_names>: Rename from...
	(symbol_set_names): ...this.
	(SYMBOL_SET_NAMES): Remove.
	(struct symbol) <ctor>: Update.

Change-Id: I8da1f10cab4e0b89f19d5750fa4e6e2ac8d2b24f