176 SbTime::formatDate() will crash on bad (?) input.

    On Windows XP, with MSVC 7, this code snippet will cause a crash:

----8<----- [snip] --------------------8<----- [snip] ----------------
    SbTime t = SbTime::getTimeOfDay();
    SbString s = t.formatDate("%T");
----8<----- [snip] --------------------8<----- [snip] ----------------

    Many other control sequences will also cause a crash, like
    e.g. "%t", or any obviously bogus sequence.

    20041207 mortene, reported by christt.

    UPDATE 20041207 mortene: looking at a call-stack backtrace, the
    crash happens within strftime().

    With GNU C (on e.g. Linux), the code will not crash.
