openssl: fix libdir issue

Closes #3205

OpenSSL's build system tries to be too wise for it's own good when
guessing what libdir should be.
This causes problems like the one reported in bug #3205 so just specify
libdir to point to /lib (since it's prefixed it would finally be
/usr/lib) since it should be present on 32 and 64 bit targets.

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