buildroot

pure-ftpd: Added pure-ftpwho config option

Added the pure-ftpwho config option. When selected, the --with-ftpwho
compiler option is passed which enabled the pure-ftpwho command.

Signed-off-by: Bryce Ferguson <bryce.ferguson@rockwellcollins.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>