PKCS#11 tests should not use CRYPTO_INVALID_SESSION
Review Request #1126 - Created July 6, 2018 and submitted
PKCS#11 defines a different value (0) than the kernel crypto framework (-1) for an invalid session. Using CRYPTO_INVALID_SESSION can cause the pkcs11 libraries to segfault (as seen if any of the current crypto tests fail).
Prior to this change, the PKCS#11 aes_ccm and aes_gcm tests could segfault in C_DestroyObject (as the PKCS#11 softtoken does not yet support those modes) w/ the first argument 0xffffffff (-1). With this change, the tests no longer segfault and merely fail (as expected due to CCM and GCM not being supported).