[PATCH 05/11] Handle const and varible modifiers for CodeView

[PATCH 05/11] Handle const and varible modifiers for CodeView

gcc/
	* dwarf2codeview.cc
	(struct codeview_custom_type): Add lf_modifier to union.
	(write_cv_padding, write_lf_modifier): New functions.
	(write_custom_types): Call write_lf_modifier.
	(get_type_num_const_type): New function.
	(get_type_num_volatile_type): Likewise.
	(get_type_num): Handle DW_TAG_const_type and DW_TAG_volatile_type DIEs.
	* dwarf2codeview.h (MOD_const, MOD_volatile): Define.
	(LF_MODIFIER): Likewise.