Drop a code path in wfBCP47() which is never reached.

count( $codeSegment ) > 0 should be never true in a foreach loop of
$codeSegment itself. See also Iffe166f3.

Change-Id: I453b5ec3379951a2ad6e34b9835907c2eba3046b
Merge "Drop a code path in wfBCP47() which is never reached."