fix for release build regarding JNI MAVLINK Methods/classes (#72)

Co-authored-by: Dimitrios Meimetis <dmeimetis@cti.gr>

Author: Jimmeimetis

app/build.gradle

@@ -28,6 +28,7 @@ android {
             minifyEnabled = true
             shrinkResources = true
             signingConfig = signingConfigs.release
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'),'proguard-rules.pro'
         }
     }
 

app/proguard-rules.pro

@@ -0,0 +1,7 @@
+-keep class com.openipc.mavlink.MavlinkData { *; }
+-keep interface com.openipc.mavlink.MavlinkUpdate { *; }
+-keep class * implements com.openipc.mavlink.MavlinkUpdate { *; }
+-keep class com.openipc.mavlink.MavlinkNative { *; }
+-keepclasseswithmembernames class * {
+    native <methods>;
+}