aircrack-ng: fix build failure and install path

aircrack-ng doesn't account that openssl needs zlib so fix it.
Fixes:
http://autobuild.buildroot.net/results/97f4f90a7d60a0e3ea81c77f6986f1c1bae8d575/



Also fix the install prefix since it was getting installed to /usr/local

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>