package/aircrack-ng: requires RC4 support in openssl

package/aircrack-ng: requires RC4 support in openssl

Enable RC4 in openssl to fix build failure when openssl is the crypto
backend of aircrack-ng.

Fixes:
http://autobuild.buildroot.net/results/007b7d88aed3902fb8ed10ee5c0ff0dc1899756d/
http://autobuild.buildroot.net/results/da464dd449bb950104122535eabf8a4e914d0a9e/
http://autobuild.buildroot.net/results/d10fec8378c334e896d9e38afe00193ef747192f/

Cc: Laurent Cans <laurent.cans@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Laurent Cans <laurent.cans@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>