PR23207, hppa ld SIGSEGVs on invalid object files

PR23207, hppa ld SIGSEGVs on invalid object files

The last patch was enough to cure the testcase, but not the original
object file.  This patch does the same for hppa as is done for ppc64,
simply test for the section belonging to a group.  I've also
restricted stubs to load, alloc, code sections.

	PR 23207
	* elf32-hppa.c (hppa_get_stub_entry): Return NULL when link_sec
	is NULL.
	(elf32_hppa_size_stubs): Only create stubs for load, alloc, code
	sections.
	(final_link_relocate): Revert last change.