Fixed issues when compiling as shared library together with PKCS#11 helper

PKCS#11 support was not really available, due to the #define being inside
a comment block in include/polarssl/config.h.

In addition, it didn't link in pkcs11-helper at all, which would make it
fail later on when PolarSSL and PKCS#11 was enabled.  Causing a build
error later on.

Signed-off-by: David Sommerseth <davids@redhat.com>