Improve logging when opening a MIDI file

* Flush debugging logs immediately after each message
* Print "Opening song" before the related log messages

src/MidiTrack.cpp

@@ -93,6 +93,7 @@ void CMidiTrack::ppDebugTrack(int level, const char *msg, ...)
     vfprintf(stdout, msg, ap);
     va_end(ap);
     fputc('\n', stdout);
+    fflush(stdout);
 }
 
 dword_t CMidiTrack::readVarLen()

src/Song.cpp

@@ -59,9 +59,9 @@ void CSong::loadSong(const QString & filename)
 #endif
     auto logLevelOk = false;
     auto logLevel = qEnvironmentVariableIntValue(PROJECT_VARNAME_UPPER "_MIDI_FILE_LOG_LEVEL", &logLevelOk);
+    ppLogInfo("Opening song %s",  fn.toLocal8Bit().data());
     m_midiFile->setLogLevel(logLevelOk ? logLevel : 3);
     m_midiFile->openMidiFile(std::string(fn.toLocal8Bit().data()));
-    ppLogInfo("Opening song %s",  fn.toLocal8Bit().data());
     transpose(0);
     midiFileInfo();
     m_midiFile->setLogLevel(99);

src/Util.cpp

@@ -71,7 +71,7 @@ static void openLogFile() {
 
 static void flushLogs()
 {
-    if (logInfoFile != stdout && logsOpened)
+    if (logInfoFile && logsOpened)
     {
         fflush(logInfoFile);
         // logErrorFile is the same as logInfoFile