Divide the code detecting ARCHIVE_HASH_*_WIN from CHECK_MD() to

Divide the code detecting ARCHIVE_HASH_*_WIN from CHECK_MD() to
clarify what CHECK_MD does. Basically, CHECK_MD prove that we
can map the HASH functions, which have several types of name, to
archive_{hash name}_init, archive_{hash name}_final and
archive_{hash name}_update through archive_hash.h.
But using ARCHIVE_HASH_*_WIN requires if ACLG_{hash name} is
available, and then __la_hash_*() used under the ARCHIVE_HASH_*_WIN
are defined at archive_windows.c. it's completely different the way
the CHECK_MD does.

SVN-Revision: 2395