Update NSPR to 4.12 and NSS to 3.23 on iOS

nss/lib/libpkix/pkix_pl_nss/module/pkix_pl_socket.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/. */
 /*
  * pkix_pl_socket.c
  *
  * Socket Function Definitions
  *
  */
 
@@ skipping 747 matching lines @@
         entry.hashcodeFunction = pkix_pl_Socket_Hashcode;
         entry.toStringFunction = NULL;
         entry.comparator = NULL;
         entry.duplicateFunction = NULL;
 
         systemClasses[PKIX_SOCKET_TYPE] = entry;
 
 #ifdef PKIX_SOCKETTRACE
         {
                 char *val = NULL;
-                val = PR_GetEnv("SOCKETTRACE");
+                val = PR_GetEnvSecure("SOCKETTRACE");
                 /* Is SOCKETTRACE set in the environment? */
                 if ((val != NULL) && (*val != '\0')) {
                         socketTraceFlag =
                                 ((*val == '1')?PKIX_TRUE:PKIX_FALSE);
                 }
         }
 #endif
 
         PKIX_RETURN(SOCKET);
 }
@@ skipping 907 matching lines @@
         PRFileDesc **pDesc,
         void *plContext)
 {
         PKIX_ENTER(SOCKET, "pkix_pl_Socket_GetPRFileDesc");
         PKIX_NULLCHECK_TWO(socket, pDesc);
 
         *pDesc = socket->clientSock;
 
         PKIX_RETURN(SOCKET);
 }