Merge glibc and coreutils changes into gnulib, plus a few

Merge glibc and coreutils changes into gnulib, plus a few
extra fixes.
* md5.c: Use #error rather than a string.
(CYCLIC): New macro, from glibc source.  Use it instead of rol.
* md5.h (__GNUC_PREREQ, __THROW): Define if not defined already.
(__attribute__): Define to empty for non recent-GCC.
(__md5_buffer, __md5_finish_ctx, __md5_init_ctx, __md5_process_block):
(__md5_process_bytes, __md5_read_ctx, __md5_stream):
Renamed from their non-__ counterparts, with new macros replacing
them if not _LIBC.  Add __THROW attribute.
(rol): Remove.
(struct md5_ctx): Align buffer if using GCC.
* sha1.h (struct sha1_ctx): Likewise.
* sha1.c (SWAP): Renamed from the NOTSWAP.  All uses changed.
The old name was backwards.
(NOTSWAP): Remove; not used.
(rol): New macro, moved here from md5.h.
(sha1_process_block): Remove a FIXME that doesn't make sense.