This is a tiny optimization (or maybe not so tiny on platforms other
than Linux where time() might not as fast as just reading a memory
location), but mostly is done to work around faketime bug[*] which
prevented it from being used for testing programs using wxWidgets, such
as our own unit tests because time() was called from wxLogTrace() in
wxCSConv::DoCreate() called when creating global conversion objects
during the library initialization.
Arguably, it might be better to avoid calling wxLogTrace() during the
initialization, but this can't be done as simply and this change might
have a small performance benefit too.
[*] https://github.com/wolfcw/libfaketime/issues/132
39dc254bf4