Update NSPR to 4.12 and NSS to 3.23 on iOS

nss/lib/pkcs7/p7local.c

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /*
  * Support routines for PKCS7 implementation, none of which are exported.
  * This file should only contain things that are needed by both the
  * encoding/creation side *and* the decoding/decryption side.  Anything
  * else should be static routines in the appropriate file.
  */
@@ skipping 693 matching lines @@
             output += ofraglen;
         }
 
         pcount = input_len - ifraglen;
         PORT_Assert (pcount < bsize);
         if (pcount)
             PORT_Memcpy (pbuf, input + ifraglen, pcount);
     }
 
     if (final) {
-        padlen = padsize - (pcount % padsize);
+        padlen = padsize ? padsize - (pcount % padsize) : 0;
         PORT_Memset (pbuf + pcount, padlen, padlen);
         rv = (* obj->doit) (obj->cx, output, &ofraglen, max_output_len,
                             pbuf, pcount+padlen);
         if (rv != SECSuccess)
             return rv;
 
         /*
          * For now anyway, all of our ciphers have the same number of
          * bytes of output as they do input.  If this ever becomes untrue,
          * then sec_PKCS7EncryptLength needs to be made smarter!
@@ skipping 586 matching lines @@
         theTemplate = SEC_PointerToPKCS7EncryptedDataTemplate;
         break;
     }
     return theTemplate;
 }
 
 /*
  * End of templates.  Do not add stuff after this; put new code
  * up above the start of the template definitions.
  */