build, android: Fix Android GUI not loading on Qt 5.15

Qt 5.14 introduced certain breaking changes to the way it parses
AndroidManifest.xml metadata

https://lists.qt-project.org/pipermail/interest/2020-January/034372.html

src/qt/android/.gitignore

@@ -1,9 +1,7 @@
 /.gradle
 /build
-/gradle/wrapper
+/gradle
 /gradlew*
 /libs
-/res/layout
-/res/values*
 /src/org/kde
 /src/org/qtproject

src/qt/android/AndroidManifest.xml

@@ -32,7 +32,8 @@
             <meta-data android:name="android.app.background_running" android:value="true"/>
             <meta-data android:name="android.app.auto_screen_scale_factor" android:value="true"/>
             <meta-data android:name="android.app.extract_android_style" android:value="default"/>
-    </activity>
+            <meta-data android:name="android.app.load_local_libs_resource_id" android:resource="@array/load_local_libs"/>
+        </activity>
 
     </application>
 </manifest>

src/qt/android/res/values/libs.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <array name="load_local_libs">
+        <item>
+            arm64-v8a;libbitcoin-qt_arm64-v8a.so
+        </item>
+        <item>
+            armeabi-v7a;libbitcoin-qt_armeabi-v7a.so
+        </item>
+        <item>
+            x86_64;libbitcoin-qt_x86_64.so
+        </item>
+        <item>
+            x86;libbitcoin-qt_x86.so
+        </item>
+    </array>
+</resources>