example 'meshtastic': add hack for faster BLE scan

examples/meshtastic/hacks/qt-bluetooth-hack/java.diff

@@ -0,0 +1,13 @@
+diff --git a/QtBluetoothLE.java.orig b/QtBluetoothLE.java
+--- a/QtBluetoothLE.java.orig
++++ b/QtBluetoothLE.java
+@@ -215,7 +215,8 @@ public class QtBluetoothLE {
+         if (isEnabled) {
+             Log.d(TAG, "New BTLE scanning API");
+             ScanSettings.Builder settingsBuilder = new ScanSettings.Builder();
+-            settingsBuilder = settingsBuilder.setScanMode(ScanSettings.SCAN_MODE_BALANCED);
++            //settingsBuilder = settingsBuilder.setScanMode(ScanSettings.SCAN_MODE_BALANCED);
++            settingsBuilder = settingsBuilder.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY); // hack for 'meshtastic'
+             ScanSettings settings = settingsBuilder.build();
+ 
+             List<ScanFilter> filterList = new ArrayList<ScanFilter>(2);

examples/meshtastic/hacks/qt-bluetooth-hack/readme.md

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+
+**android only**
+
+
+Why
+---
+
+Not strictly necessary, but this enables faster BLE scan mode, like in the
+official 'meshtastic' android app.
+
+
+HowTo
+-----
+
+Install the Qt5.15 sources and do:
+```
+$ cd <qt-sources>/qtconnectivity/src/android/bluetooth/src/org/qtproject/qt5/android/bluetooth
+```
+* apply patch `java.diff`
+```
+$ cd <qt-sources>/qtconnectivity/src/android/bluetooth
+$ qmake-android bluetooth.pro
+$ make
+$ chmod +x ~/Qt/5.15.2/android/jar/QtAndroidBluetooth.jar
+```
+