Update return value from EVP_Encode_Update in one error case (#1499)

Coverity pointed that total was not used in this `if` statement which
returns right away. It was because of introducing the return statements
in
6d9a767.
The comments indicate that the intention is to update out_len as on line
180.

crypto/base64/base64.c

@@ -193,7 +193,7 @@ int EVP_EncodeUpdate(EVP_ENCODE_CTX *ctx, uint8_t *out, int *out_len,
   if (total > INT_MAX) {
     // We cannot signal an error, but we can at least avoid making *out_len
     // negative.
-    total = 0;
+    *out_len = 0;
     return 0;
   }
   *out_len = (int)total;