Fix shadowed variable warning

libvirtd.c: In function 'daemonSetupAccessManager':
libvirtd.c:730:18: error: declaration of 'driver' shadows
  a global declaration [-Werror=shadow]
     const char **driver = (const char **)config->access_drivers;
                  ^
In file included from libvirtd.c:95:0:
../src/node_device/node_device_driver.h:43:36: error: shadowed
  declaration is here [-Werror=shadow]
 extern virNodeDeviceDriverStatePtr driver;
                                    ^

daemon/libvirtd.c

@@ -727,13 +727,13 @@ daemonSetupAccessManager(struct daemonConfig *config)
 {
     virAccessManagerPtr mgr;
     const char *none[] = { "none", NULL };
-    const char **driver = (const char **)config->access_drivers;
+    const char **drv = (const char **)config->access_drivers;
 
-    if (!driver ||
-        !driver[0])
-        driver = none;
+    if (!drv ||
+        !drv[0])
+        drv = none;
 
-    if (!(mgr = virAccessManagerNewStack(driver)))
+    if (!(mgr = virAccessManagerNewStack(drv)))
         return -1;
 
     virAccessManagerSetDefault(mgr);