configure: remove bashism

Commit e26110cf added a check for shacmd to create a hash
for modules.  This check in configure is using bash construct &>
to redirect both stdout and stderr, which does fun things on some
shells.  Get rid of it, use standard redirection instead.
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>
Reviewed-by: NFam Zheng <famz@redhat.com>
(cherry picked from commit 4fc00556)
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

configure

@@ -2624,7 +2624,7 @@ done
 if test "$modules" = yes; then
     shacmd_probe="sha1sum sha1 shasum"
     for c in $shacmd_probe; do
-        if which $c &>/dev/null; then
+        if which $c >/dev/null 2>&1; then
             shacmd="$c"
             break
         fi