Fixes for LP Bug #1797746 / noquote for QT5

Fix for https://bugs.launchpad.net/mixxx/+bug/1797746

Without this patch, debugging messages in mixxx.log are
quoted since QT > 5.4, which breaks output of engine.log()
escape characters.

This patch adds .noquote() to QDebug if QT_VERSION >= 5.4

src/controllers/controllerdebug.h

@@ -30,10 +30,17 @@ class ControllerDebug {
 // We prefix every log message with Logging::kControllerDebugPrefix so that we
 // can bypass the --logLevel commandline argument when --controllerDebug is
 // specified.
+//
+// In order of Bug #1797746, since transition to qt5 it is needed unquote the
+// output for mixxx.log with .noquote(), because in qt5 QDebug() is quoted by default.
 #define controllerDebug(stream)       \
 {                                     \
     if (ControllerDebug::enabled()) { \
+#if QT_VERSION > 0x050399
+        QDebug(QtDebugMsg).noquote() << ControllerDebug::kLogMessagePrefix << stream; \
+#else
         QDebug(QtDebugMsg) << ControllerDebug::kLogMessagePrefix << stream; \
+#endif
     }                                 \
 }                                     \