sys: don't start privops helper for NTS-KE helper

The NTS-KE helper doesn't need to bind sockets or adjust the clock.
Don't start the privops helper, or keep the capabilities, when dropping
root privileges in its context.

sys_solaris.c

@@ -57,7 +57,8 @@ SYS_Solaris_Finalise(void)
 void
 SYS_Solaris_DropRoot(uid_t uid, gid_t gid, SYS_ProcessContext context)
 {
-  PRV_StartHelper();
+  if (context == SYS_MAIN_PROCESS)
+    PRV_StartHelper();
   UTI_DropRoot(uid, gid);
 }
 #endif