PR32690, assertion failure in lang_size_relro_segment

This introduces a new function which should be used whenever the
linker needs to increase section alignment after mapping input to
output sections.

	PR ld/32690
	* linker.c (bfd_link_align_section): New function.
	* elflink.c (_bfd_elf_adjust_dynamic_copy): Use it.
	* bfd-in2.h: Regenerate.