gdb: move Modula2 language class into a header file

gdb: move Modula2 language class into a header file

Move the m2_language class from m2-lang.c into m2-lang.h.  The benefit
of this move is that we can remove trampoline functions.  Currently
the language implementation is split of different m2-* files with
m2-lang.h including declaration for all the language implementation
functions.

Currently the m2_language class in m2-lang.c has member functions that
then call the global functions declared in m2-lang.h.

After this change the m2_language class is declared in m2-lang.h, and
the member functions are the implementations defined in all the m2-*
files.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* m2-exp.y (m2_parse): Rename to...
	(m2_language::parser): ...this.  Update function signature.
	* m2-lang.c (m2_printchar): Renamed to m2_language::printchar.
	(m2_op_print): Rename to...
	(m2_language::op_print_tab): ...this, and make const.
	(exp_descriptor_modula2): Rename to...
	(m2_language::exp_descriptor_modula2): ...this.
	(class m2_language): Move to m2-lang.h.
	(m2_language::language_arch_info): New function, moved out of
	class declaration.
	(m2_language::printchar): New function, body from m2_printchar.
	(m2_language::printstr): New function, moved out of class
	declaration.
	(m2_language::emitchar): Likewise.
	* m2-lang.h (m2_parse): Delete declaration.
	(m2_print_typedef): Delete declaration.
	(m2_value_print_inner): Delete declaration.
	(class m2_language): Class declaration moved from m2-lang.c,
	larger functions are left in m2-lang.c.
	* m2-typeprint.c (m2_print_typedef): Rename to...
	(m2_language::print_typedef): ...this, and update function
	signature.
	* m2-valprint.c (m2_value_print_inner): Rename to...
	(m2_language::value_print_inner): ...this, replace use of
	LA_PRINT_STRING with a direct call to printstr member function,
	and update recursive call.