gdb: Convert language la_emitchar field to a method

This commit changes the language_data::la_emitchar function pointer
member variable into a member function of language_defn.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* ada-lang.c (emit_char): Renamed to ada_language::emitchar.
	(ada_language_data): Delete la_emitchar initializer.
	(ada_language::emitchar): New member function, implementation from
	emit_char.
	* c-lang.c (c_language_data): Delete la_emitchar initializer.
	(cplus_language_data): Likewise.
	(asm_language_data): Likewise.
	(minimal_language_data): Likewise.
	* d-lang.c (d_language_data): Likewise.
	* f-lang.c (f_emit_char): Rename to f_language::emitchar.
	(f_language_data): Delete la_emitchar initializer.
	(f_language::emitchar): New member function, implementation from
	f_emit_char.
	* go-lang.c (go_language_data): Delete la_emitchar initializer.
	* language.c (unk_lang_emit_char): Delete.
	(language_defn::emitchar): New member function definition.
	(unknown_language_data): Delete la_emitchar initializer.
	(unknown_language::emitchar): New member function.
	(auto_language_data): Delete la_emitchar initializer.
	(auto_language::emitchar): New member function.
	* language.h (language_data): Delete la_emitchar field.
	(language_defn::emitchar): New member field declaration.
	(LA_EMIT_CHAR): Update call to emitchar.
	* m2-lang.c (m2_emit_char): Rename to m2_language::emitchar.
	(m2_language_data): Delete la_emitchar initializer.
	(m2_language::emitchar): New member function, implementation from
	m2_emit_char.
	* objc-lang.c (objc_language_data): Delete la_emitchar
	initializer.
	* opencl-lang.c (opencl_language_data): Likewise.
	* p-lang.c (pascal_emit_char): Rename to pascal_language::emitchar.
	(pascal_language_data): Delete la_emitchar initializer.
	(pascal_language::emitchar): New member function, implementation
	from pascal_emit_char.
	* rust-lang.c (rust_emitchar): Rename to rust_language::emitchar.
	(rust_language_data): Delete la_emitchar initializer.
	(rust_language::emitchar): New member function, implementation
	from rust_emitchar.