hppa64: Initial relro support for Linux

This also fixes the alignment of the data segment on Linux target.
It must be page aligned to avoid inequivalent aliases.

2026-04-04  John David Anglin  <danglin@gcc.gnu.org>

	PR ld/12376

bfd/ChangeLog:

	* elf64-hppa.c (elf_backend_modify_segment_map): Don't
	use HP-UX specific routine on Linux.
	(elf_backend_want_dynrelro): Define to 1 on Linux.

ld/ChangeLog:

	* emulparams/hppa64linux.sh (COMMONPAGESIZE): Define.
	(DATA_SEGMENT_ALIGN, DATA_SEGMENT_END,
	DATA_SEGMENT_RELRO_END): Define if $LD_FLAG != "N".
	(DATA_SECTION_ALIGNMENT): Define.
	* scripttempl/elf64hppa.sc: Revise handling of data
	segment.
	* testsuite/ld-elf/orphan-region.d: Remove xfail on
	Linux.