r13255: New CIFS dd client for use in performance testing. The guts of this is

r13255: New CIFS dd client for use in performance testing. The guts of this is
in client/cifsdd*, which implements a minimal implementation of dd. The
IO path is careful to always perform IO at the requested block size.

There is a very basic test suite in script/tests/test_cifsdd.sh which
covers local and remote IO at a variety of block sizes.

Added to lib/util_str.c is a small set of conv_str_*() functions to
convert strings to the corresponding type.

smbcli_parse_unc is modified to insert NULL terminators after its
hostname and sharename parameters. This allows it to correctly parse a
path of the form //foo/share/path/file.