man: Use -w instead of --path

--path is an alias command line option for -w.
It is available since man-db 2.6.1-pre1 (2012-02-05).

See commit:
http://git.savannah.gnu.org/cgit/man-db.git/commit/?id=e37bc92f352c97c61ef63de745e43574d27b1276

For portability (like man-1.6g), prefer using original -w switch.

Signed-off-by: Matthieu Crapet <mcrapet@gmail.com>
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