gdb: Convert language la_compute_program field to a method

gdb: Convert language la_compute_program field to a method

This commit changes the language_data::la_compute_program 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 (ada_language_data): Delete la_compute_program
	initializer.
	* c-lang.c (c_language_data): Likewise.
	(c_language::compute_program): New member function.
	(cplus_language_data): Delete la_compute_program initializer.
	(cplus_language::compute_program): New member function.
	(asm_language_data): Delete la_compute_program initializer.
	(minimal_language_data): Likewise.
	* c-lang.h (c_compute_program): Update comment.
	(cplus_compute_program): Likewise.
	* compile/compile-c-support.c (c_compute_program): Likewise.
	(cplus_compute_program): Likewise.
	* compile/compile.c (compile_to_object): Update call to
	la_compute_program.
	* d-lang.c (d_language_data): Delete la_compute_program
	initializer.
	* f-lang.c (f_language_data): Likewise.
	* go-lang.c (go_language_data): Likewise.
	* language.c (unknown_language_data): Likewise.
	(auto_language_data): Likewise.
	* language.h (language_data): Delete la_compute_program field.
	(language_defn::compute_program): New member function.
	* m2-lang.c (m2_language_data): Delete la_compute_program
	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.