Fix troublesome mlock() calls

@@ -110,10 +110,10 @@ int xc_hvm_set_pci_intx_level(
     arg.intx   = intx;
     arg.level  = level;
 
-    if ( mlock(&arg, sizeof(arg)) != 0 )
+    if ( (rc = lock_pages(&arg, sizeof(arg))) != 0 )
     {
         PERROR("Could not lock memory");
-        return -1;
+        return rc;
     }
 
     rc = do_xen_hypercall(xc_handle, &hypercall);

@@ -140,10 +140,10 @@ int xc_hvm_set_isa_irq_level(
     arg.isa_irq = isa_irq;
     arg.level   = level;
 
-    if ( mlock(&arg, sizeof(arg)) != 0 )
+    if ( (rc = lock_pages(&arg, sizeof(arg))) != 0 )
     {
         PERROR("Could not lock memory");
-        return -1;
+        return rc;
     }
 
     rc = do_xen_hypercall(xc_handle, &hypercall);

@@ -168,10 +168,10 @@ int xc_hvm_set_pci_link_route(
     arg.link    = link;
     arg.isa_irq = isa_irq;
 
-    if ( mlock(&arg, sizeof(arg)) != 0 )
+    if ( (rc = lock_pages(&arg, sizeof(arg))) != 0 )
     {
         PERROR("Could not lock memory");
-        return -1;
+        return rc;
     }
 
     rc = do_xen_hypercall(xc_handle, &hypercall);