fmt hoisted to global.

`fmt` was being hoisted as a global variable.
Signed-off-by: Nick Campbell <nicholas.j.campbell@gmail.com>

jquery.flot.time.js

@@ -272,6 +272,7 @@ for details.
                         var suffix = (opts.twelveHourClock) ? " %p" : "";
                         var hourCode = (opts.twelveHourClock) ? "%I" : "%H";
                         
+                        var fmt;
                         if (t < timeUnitSize.minute)
                             fmt = hourCode + ":%M:%S" + suffix;
                         else if (t < timeUnitSize.day) {