currently JTReg ca get PIT of test process only if we use JDK 9 as stable JDK or if we are running on *nix system. however after CODETOOLS-7901452, we can extend JTReg to get PIT on other systems as well.

for windows, we should use well-know win32 API GetProcessId using value of java.lang.Win32Process::handle as the argument.