Use *args inside FAIL and SKIP so that it is possible to call these functions

with multiple arguments, printf style.  This is already being done in some
cases (causing an exception of course).

Signed-off-by: Ewan Mellor <ewan@xensource.com>

tools/xm-test/lib/XmTestLib/Test.py

@@ -131,12 +131,12 @@ def becomeNonRoot():
         if os.geteuid() == 0:
             FAIL("Could not become a non-root user")
 
-def FAIL(reason):
-    print "\nREASON: %s" % reason
+def FAIL(format, *args):
+    print "\nREASON:", (format % args)
     sys.exit(TEST_FAIL)
 
-def SKIP(reason):
-    print "\nREASON: %s" % reason
+def SKIP(format, *args):
+    print "\nREASON:", (format % args)
     sys.exit(TEST_SKIP)
 
 def saveLog(logText, filename=None):