android: don't default to making libre builds

android/build.gradle

     glideVersion = "4.7.1"  // keep in sync with react-native-fast-image
 
     // Libre build
-    libreBuild = (System.env.LIBRE_BUILD ?: "true").toBoolean()
+    libreBuild = (System.env.LIBRE_BUILD ?: "false").toBoolean()
 }
 
 // If Android SDK is not installed, accept its license so that it