Re-enabled std.internal.processinit

Apparently, this was added at some point to avoid cyclic module
dependencies.
Workaround for unintentionally public imports

It seems that the test failures were caused by this:

    private:
    ...
    public:
    ...
    import something;

Thus, some imports were unintentionally made public. This has allowed me
to also revert an earlier change to std.file, which was a workaround for
those failures