Remove KNI support

Not funny, reland it when we really need Kotlin Native

app/src/main/java/com/hippo/Native.kt

@@ -18,20 +18,12 @@
 package com.hippo
 
 import java.io.FileDescriptor
-import java.nio.ByteBuffer
 
 object Native {
     fun initialize() {
         System.loadLibrary("ehviewer")
-        System.loadLibrary("ehviewer_kotlin_native")
     }
 
     @JvmStatic
     external fun getFd(fd: FileDescriptor?): Int
-
-    @JvmStatic
-    external fun mapFd(fd: Int, capability: Long): ByteBuffer?
-
-    @JvmStatic
-    external fun unmapDirectByteBuffer(buffer: ByteBuffer)
 }