Also create pid file in non-daemon mode

Always make a pid file, not only when `-daemon` specified.

This is useful for troubleshooting, for attaching debuggers and loggers
and such.

- Write the pid file only after the datadir lock was acquired
- Don't create or remove a pid file on WIN32, and also don't show the option

src/bitcoind.cpp

@@ -129,7 +129,6 @@ bool AppInit(int argc, char* argv[])
             }
             if (pid > 0) // Parent process, pid is child process id
             {
-                CreatePidFile(GetPidFile(), pid);
                 return true;
             }
             // Child process falls through to rest of initialization