[bfd] Revise import stubs on hppa.

	[bfd] Revise import stubs on hppa.

	This commit updates the import stubs to leave the pointer to the
	function descriptor in register %r22.  This provides a backup
	mechanism for _dl_runtime_resolve to fixup descriptors during
	lazy binding.

	bfd/ChangeLog
	2019-10-20  John David Anglin  <danglin@gcc.gnu.org>

		* elf32-hppa.c: Revise import stub sequences.
		(LONG_BRANCH_STUB_SIZE): Define.
		(LONG_BRANCH_SHARED_STUB_SIZE): Define.
		(IMPORT_STUB_SIZE): Define.
		(IMPORT_SHARED_STUB_SIZE): Define.
		(EXPORT_STUB_SIZE): Define.
		(plt_stub): Revise to not use register %r22.
		(LDO_R1_R22): Define.
		(LDW_R22_R21): Define.
		(LDW_R22_R19): Define.
		(hppa_build_one_stub): Update stub generation and use new defines.
		(hppa_size_one_stub): Likewise.