gdb: Convert la_store_sym_names_in_linkage_form_p to a method

Convert language_data::la_store_sym_names_in_linkage_form_p member
variable to language_defn::store_sym_names_in_linkage_form_p virtual
function.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* ada-lang.c (ada_language_data): Remove
	la_store_sym_names_in_linkage_form_p initializer.
	(ada_language::store_sym_names_in_linkage_form_p): New member
	function.
	* c-lang.c (c_language_data): Remove
	la_store_sym_names_in_linkage_form_p initializer.
	(c_language::store_sym_names_in_linkage_form_p): New member
	function.
	(cplus_language_data): Remove la_store_sym_names_in_linkage_form_p
	initializer.
	(asm_language_data): Likewise.
	(asm_language::store_sym_names_in_linkage_form_p): New member
	function.
	(minimal_language_data): Remove
	la_store_sym_names_in_linkage_form_p initializer.
	(minimal_language::store_sym_names_in_linkage_form_p): New member
	function.
	* d-lang.c (d_language_data): Remove
	la_store_sym_names_in_linkage_form_p initializer.
	* dwarf2/read.c (dwarf2_physname): Update call to
	store_sym_names_in_linkage_form_p.
	* f-lang.c (f_language_data): Remove
	la_store_sym_names_in_linkage_form_p initializer.
	* go-lang.c (go_language_data): Remove
	la_store_sym_names_in_linkage_form_p initializer.
	* language.c (unknown_language_data): Remove
	la_store_sym_names_in_linkage_form_p initializer.
	(unknown_language::store_sym_names_in_linkage_form_p): New member
	function.
	(auto_language_data): Remove la_store_sym_names_in_linkage_form_p
	initializer.
	(auto_language::store_sym_names_in_linkage_form_p): New member
	function.
	* language.h (language_data): Remove
	la_store_sym_names_in_linkage_form_p member variable.
	(language_defn::store_sym_names_in_linkage_form_p): New member
	function.
	* m2-lang.c (m2_language_data): Remove
	la_store_sym_names_in_linkage_form_p initializer.
	* objc-lang.c (objc_language_data): Likewise.
	* opencl-lang.c (opencl_language_data): Likewise.
	* p-lang.c (pascal_language_data): Likewise.
	* rust-lang.c (rust_language_data): Likewise.