Revert "ld: Rewrite lang_size_relro_segment_1"

This reverts commit c804c6f9.

	PR ld/28743
	PR ld/28819
	* ldlang.c (lang_size_relro_segment_1): Revert 2022-01-14 change.
	* testsuite/ld-x86-64/pr28743-1.d: Likewise.
	* testsuite/ld-x86-64/pr28743-1.s: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.