flag_complex_method: support optimize attribute

flag_complex_method: support optimize attribute

gcc/c-family/ChangeLog:

	* c-opts.c (c_common_init_options_struct): Set also
	  x_flag_default_complex_method.

gcc/ChangeLog:

	* common.opt: Add new variable flag_default_complex_method.
	* opts.c (finish_options): Handle flags related to
	  x_flag_complex_method.
	* toplev.c (process_options): Remove option handling related
	to flag_complex_method.

gcc/go/ChangeLog:

	* go-lang.c (go_langhook_init_options_struct): Set also
	  x_flag_default_complex_method.

gcc/lto/ChangeLog:

	* lto-lang.c (lto_init_options_struct): Set also
	  x_flag_default_complex_method.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/compile/attr-complex-method-2.c: New test.
	* gcc.c-torture/compile/attr-complex-method.c: New test.