zdtm.py: chdir to dir the py script is in

It allows to execute zdtm.py not only from the test directory.
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.py

@@ -17,6 +17,8 @@ import string
 import imp
 import socket
 
+os.chdir(os.path.dirname(os.path.abspath(__file__)))
+
 prev_line = None
 def traceit(f, e, a):
 	if e == "line":