Make the 'lxc_driver' global variable non-static

The 'lxc_driver' global variable is now used from several of
the LXC sources files. Thus it needs to be non-static to
avoid runtime linkage errors
Signed-off-by: NGao feng <gaofeng@cn.fujitsu.com>

src/lxc/lxc_driver.c

@@ -72,7 +72,7 @@
 
 static int lxcStartup(int privileged);
 static int lxcShutdown(void);
-static lxc_driver_t *lxc_driver = NULL;
+lxc_driver_t *lxc_driver = NULL;
 
 /* Functions */