Make sure that LOOP_CTL_GET_FREE is defined.

Signed-off-by: Lucas C. Villa Real <lucasvr@gobolinux.org>

--- udisks-1.97.0/src/udiskslinuxmanager.c.orig	2012-05-21 17:18:27.000000000 -0300
+++ udisks-1.97.0/src/udiskslinuxmanager.c	2012-05-21 17:18:56.000000000 -0300
@@ -43,6 +43,10 @@
 #include "udiskscleanup.h"
 #include "udiskslinuxblockobject.h"
 
+#ifndef LOOP_CTL_GET_FREE
+#define LOOP_CTL_GET_FREE 0x4C82
+#endif
+
 /**
  * SECTION:udiskslinuxmanager
  * @title: UDisksLinuxManager