Fix potential memory leak in RSAPSS (#1186)

When creating a new context with ICC_EVP_MD_CTX_new potential failures
can occur. In the case that this API fails we should release the entire
ockDigest structure upon failure.

Fixes: #1138

Back-ported from: #1169

Signed-off-by: Jason Katonica <katonica@us.ibm.com>

Author: jasonkatonica

src/main/native/ock/RsaPss.c

@@ -548,6 +548,7 @@ OCKDigest *allocateDigest(JNIEnv *env, ICC_CTX *ockCtx, jstring digestAlgo) {
         if (NULL == ockDigest->mdCtx) {
             ockCheckStatus(ockCtx);
             throwOCKException(env, 0, "ICC_EVP_MD_CTX_new failed");
+            FREE_N_NULL(ockDigest);
         } else {
             ICC_EVP_MD_CTX_init(ockCtx, ockDigest->mdCtx);
         }