buildroot

package/strongswan: Install libraries to /usr/lib

Install strongswan ipsec libraries into /usr/lib instead of
/usr/lib/ipsec to place them in preferred library common location.

Signed-off-by: Sam Voss <sam.voss@rockwellcollins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>