kotlinc-jvm/kotlinc-js fixes

This patch makes the currently-required preloader profiling argument (`time|notime`) an optional switch (`-pp`) in the compiler scripts. It doesn't affect the preloader's argument processing.

AFAICT, preloader profiling is a diagnostic/tuning feature rather than something that users of the compiler tools *need* to think about. Making it optional ensures third-party wrappers continue to work and allows the implementation to change (or be removed altogether) without breaking tools that depend on these scripts.

The patch also cleans up and fixes some issues with the Windows batch files, which look like they haven't been used for a while. There may still be some issues remaining. I don't have access to Windows, so I can't test them.