[tz] cppcheck in-efficiencies

I use cppcheck to scan my code, and it found these in-efficiencies, Could somebody fix them ? date/tz.cpp:755: performance: Variable 'u' is assigned in constructor body. Consider performing initialization in initialization list. date/date.h:7218: performance: Function parameter 'format' should be passed by reference. date/tz.cpp:220: performance: Function parameter 'path' should be passed by reference. date/tz.cpp:2417: performance: Function parameter 'format' should be passed by reference. Khamit Ardashev Flextrade Systems