[Process] Fixed Process to work on Windows with CgiHttpKernel (2.0)

- A working directory that does not exist does not work.
- Descriptors formatting.
- stream_set_blocking() takes integer not boolean as second parameter.
- Streams on Windows that didn't set to non-blocking should only fread()
  when there are bytes to read and only fclosed() while being eof. Fixes
  PHP Bug #51800 (for 2.2, not for 2.0).
- Added ProcessStreams incl. support to have read and write descriptors
  both as pipes or tempfiles.
- Changed callback calls (internal callbacks, external callbacks unchanged).
- ProcessTest::testProcessPipes() should work on windows again.