md5.h, md5.c: updated to latest version from gnulib.

md5.h, md5.c: updated to latest version from gnulib.
Buggy old md5.h causes problems with gcc 4.3 compiler.  In
md5.h __attribute__ is #define'd to no-op and causes mutt_md5
to enter inifinite loop while calling memcpy().

Signed-off-by: Alexey I. Froloff <raorn@altlinux.org>
---
 md5.c |  167 +++++++++++++++++++++++++++++++++--------------------------------
 md5.h |   21 ++------
 2 files changed, 90 insertions(+), 98 deletions(-)