Define MAP_STACK and MAP_HUGETLB on powerpc, s390, sh and sparc.

	* sysdeps/unix/sysv/linux/powerpc/bits/mman.h: Define MAP_STACK and
	MAP_HUGETLB.
	* sysdeps/unix/sysv/linux/s390/bits/mman.h: Likewise.
	* sysdeps/unix/sysv/linux/sh/bits/mman.h: Likewise.
	* sysdeps/unix/sysv/linux/sparc/bits/mman.h: Likewise.