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/util.cpp

@@ -472,6 +472,7 @@ void ReadConfigFile(map<string, string>& mapSettingsRet,
     ClearDatadirCache();
 }
 
+#ifndef WIN32
 boost::filesystem::path GetPidFile()
 {
     boost::filesystem::path pathPidFile(GetArg("-pid", "bitcoind.pid"));
@@ -479,7 +480,6 @@ boost::filesystem::path GetPidFile()
     return pathPidFile;
 }
 
-#ifndef WIN32
 void CreatePidFile(const boost::filesystem::path &path, pid_t pid)
 {
     FILE* file = fopen(path.string().c_str(), "w");