[bfd] Provide 8-byte minimum alignment for .plt section

	[bfd]	Provide 8-byte minimum alignment for .plt section

	This change increases the default alignment for the .plt section
	from 4 bytes to 8 bytes.  When function descriptors are 8-byte
	aligned, they can be updated atomically on 32-bit hppa.  This
	helps with ordering issues on SMP machines.  It also ensures
	that descriptors reside on the same cache line.  This reduces
	the probability of a double TLB miss in a call.

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

		* elf32-hppa.c (elf32_hppa_size_dynamic_sections): Provide 8-byte
		minimum alignment for .plt section.