elf: Copy p_align of PT_GNU_STACK for stack alignment

commit 74e315db
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Mon Dec 13 19:46:04 2021 -0800

    elf: Set p_align to the minimum page size if possible

may ignore p_align of PT_GNU_STACK when copying ELF program header if
the maximum page size is larger than p_align of PT_LOAD segments.  Copy
p_align of PT_GNU_STACK since p_align of PT_GNU_STACK describes stack
alignment, not page size,

	PR binutils/29319
	* elf.c (copy_elf_program_header): Copy p_align of PT_GNU_STACK
	for stack alignment.