gdb: Convert language_data::la_range_check to a method

gdb: Convert language_data::la_range_check to a method

Convert language_data::la_range_check member variable to a virtual
method language_defn::range_checking_on_by_default.

Where the previous member variable was of type 'enum range_check', the
new member function returns a boolean that selects between range
checking being on or off.  This removes the possibility of a language
having its default be the third enum state, range_check_warn, which
no language currently used.

This all makes sense I think, the language's true/false provides the
default when the global 'set check range' is set to 'auto'.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* ada-lang.c (ada_language_data): Remove la_range_check
	initializer.
	* c-lang.c (c_language_data): Likewise.
	(cplus_language_data): Likewise.
	(asm_language_data): Likewise.
	(minimal_language_data): Likewise.
	* d-lang.c (d_language_data): Likewise.
	* f-lang.c (f_language_data): Likewise.
	(f_language::range_checking_on_by_default): New member function.
	* go-lang.c (go_language_data): Remove la_range_check initializer.
	* language.c (enum range_mode): Moved here from language.h.
	(range_mode): Made static.
	(show_range_command): Update to use
	range_checking_on_by_default.
	(set_range_command): Likewise.
	(set_range_case): Likewise.
	(unknown_language_data): Remove la_range_check initializer.
	(auto_language_data): Likewise.
	* language.h (range_mode): Delete.  Enum definition moved to
	language.c.
	(language_data): Remove la_range_check field.
	(language_defn::range_checking_on_by_default): New member
	function.
	* m2-lang.c (m2_language_data): Remove la_range_check initializer.
	(m2_language::range_checking_on_by_default): New member function.
	* objc-lang.c (objc_language_data): Remove la_range_check
	initializer.
	* opencl-lang.c (opencl_language_data): Likewise.
	* p-lang.c (pascal_language_data): Likewise.
	(pascal_language::range_checking_on_by_default): New member
	function.
	* rust-lang.c (rust_language_data): Remove la_range_check
	initializer.
	(rust_language::range_checking_on_by_default): New member
	function.