fix(driver): avoid 'untrusted location' notice with per-server network driver

 - When determining the server, fall back to drvPtr->defMapPtr whenever mapPtr is NULL
   (removed dependency on sockPtr->servPtr).
 - Treat missing route mapping identically for global and per-server driver installs.
 - Eliminates misleading Notice logs such as:
    * ... serving request to server 'xxxx' with untrusted location ...
    * ... consider loading driver nssock globally in section 'ns/modules' ...

 - Rationale: When no map entry exists, the default map (defMapPtr)
   must be used regardless of installation mode; the previous
   condition only applied the fallback for globally installed drivers,
   producing spurious warnings with per-server nssock.

This change reduces noisy logging for per-server setups. There is no
functional change for globally installed drivers.

Author: gustafn

nsd/driver.c

@@ -5872,10 +5872,10 @@ SockSetServer(Sock *sockPtr)
                reqPtr->request.line, (void*)sockPtr->servPtr);
     }
 
-    if (mapPtr == NULL && sockPtr->servPtr == NULL) {
+    if (mapPtr == NULL) {
         /*
-         * The driver is installed globally, fall back to the default server,
-         * which has to be defined in this case.
+         * If we have no mapPtr, fall back to the default server. This applies
+         * the same way for global and per-server drivers.
          */
         mapPtr = drvPtr->defMapPtr;
         Ns_Log(DriverDebug, "SockSetServer: get default map entry %p", (const void*)mapPtr);