Use a member function to set a symbol's language

Use a member function to set a symbol's language

This removes symbol_set_language and SYMBOL_SET_LANGUAGE in favor of
a new function general_symbol_info::set_language. symbol and minimal_symbol
already inherit from that struct so this works naturally.

gdb/ChangeLog:

2019-12-15  Christian Biesinger  <cbiesinger@google.com>

	* ada-exp.y (write_ambiguous_var): Update.
	* coffread.c (process_coff_symbol): Update.
	* ctfread.c (ctf_add_enum_member_cb): Update.
	(new_symbol): Update.
	* dwarf2read.c (fixup_go_packaging): Update.
	(new_symbol): Update.
	* language.c (language_alloc_type_symbol): Update.
	* mdebugread.c (new_symbol): Update.
	* minsyms.c (minimal_symbol_reader::record_full): Update.
	* psymtab.c (add_psymbol_to_bcache): Update.
	* stabsread.c (define_symbol): Update.
	(read_enum_type): Update.
	* symtab.c (symbol_set_language): Make this a member function...
	(general_symbol_info::set_language): ... here.
	* symtab.h (struct general_symbol_info) <set_language>: New function.
	(SYMBOL_SET_LANGUAGE): Remove.
	(symbol_set_language): Remove.

Change-Id: Ideafb6c384004b9adef793a1192735c501da41d5