Fix error handling in lhash contract

When the realloc fails in contract, this not a fatal
error, since the memory is only shrinked. It is also no
option to exit the function at this point, since that
would leave the hash table in an inconsistent state.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from #22154)

(cherry picked from commit 5fbfd64)

crypto/lhash/lhash.c

@@ -266,12 +266,12 @@ static void contract(OPENSSL_LHASH *lh)
         if (n == NULL) {
             /* fputs("realloc error in lhash",stderr); */
             lh->error++;
-            return;
+        } else {
+            lh->b = n;
         }
         lh->num_alloc_nodes /= 2;
         lh->pmax /= 2;
         lh->p = lh->pmax - 1;
-        lh->b = n;
     } else
         lh->p--;