files: do not call free on the result of dirname

This fixes https://savannah.gnu.org/bugs/?47544,
and thus also http://gnats.netbsd.org/51010.

Reported-by: Adrian Siekierka <asiekierka@gmail.com>
Reported-by: Matthew Hall <mhall@mhcomputing.net>
Signed-off-by: Benno Schulenberg <bensberg@justemail.net>
1 file changed