ld: Add lang_size_relro_segment

ld: Add lang_size_relro_segment

Break lang_size_sections down into separate functions so that they can
also be used for text-only LOAD segment.  lang_size_relro_segment will
call lang_size_relro_segment_1 and lang_size_segment for both GNU_RELRO
segment and text-only LOAD segment.

	* ldlang.c (lang_size_segment): New function.
	(lang_size_relro_segment_1): Likewise.
	(lang_size_relro_segment): Likewise.
	(lang_size_sections): Rewrite to call lang_size_relro_segment.