ld: Add ldlang_check_relro_region/update lang_find_relro_sections_1

ld: Add ldlang_check_relro_region/update lang_find_relro_sections_1

Extract GNU_RELRO region check into a new funtion and pass a pointer to
seg_align_type to lang_find_relro_sections_1 so that they can also be
used for text-only LOAD segment.

	* ldlang.c (lang_size_sections_1): Extract GNU_RELRO region check
	into ...
	(ldlang_check_relro_region): New function.
	(lang_find_relro_sections_1): Add an argument for pointer to
	seg_align_type and replace expld.dataseg with the pointer.
	(lang_find_relro_sections): Pass address of expld.dataseg to
	lang_find_relro_sections_1.