android: keep jniLibs compressed after the minSdk 23 bump

minSdk 23 flipped AGP's useLegacyPackaging default to false (uncompressed
.so, extractNativeLibs=false): the APK grew 12 -> 23 MB.  Updates are
downloaded over cellular, so pin useLegacyPackaging = true; APK is back
to ~12 MB (2.14.0 re-published with the same versionCode, sha updated in
the manifest before any device fetched it).

src/frontends/android/app/build.gradle

@@ -31,6 +31,15 @@ def keystoreKeyPassword = envOr('KEY_PASSWORD', '')
 android {
     namespace = 'org.strongswan.android'
 
+    /* minSdk 23 flipped AGP's default to uncompressed .so (extractNativeLibs=false):
+     * the APK grew 12 -> 23 MB.  Updates are downloaded over cellular, so keep
+     * the libraries compressed as before. */
+    packaging {
+        jniLibs {
+            useLegacyPackaging = true
+        }
+    }
+
     defaultConfig {
         applicationId "one.shx.strongswan.ext"
         compileSdk = 36