crt: exe: Enable per-thread locale if user asked for it

There is missing call _configthreadlocale(-1) in pre_c_init function.
Startup code from Visual C++ runtime is doing same thing.

This applies only for msvcr80+ and UCRT builds. For older msvcrt versions
there is only empty wrapper.

Signed-off-by: Martin Storsjö <martin@martin.st>