Remove unused files in native directory

native/build.gradle.kts

@@ -1,32 +0,0 @@
-plugins {
-    id("com.android.library")
-}
-
-setupCommon()
-
-android {
-    namespace = "com.topjohnwu.magisk.binary"
-
-    externalNativeBuild {
-        ndkBuild {
-            path("src/Android.mk")
-        }
-    }
-
-    sourceSets.getByName("main") {
-        manifest.srcFile("src/AndroidManifest.xml")
-    }
-
-    defaultConfig {
-        externalNativeBuild {
-            ndkBuild {
-                // Pass arguments to ndk-build.
-                arguments(
-                    "B_MAGISK=1", "B_INIT=1", "B_BOOT=1", "B_POLICY=1",
-                    "B_PRELOAD=1", "B_PROP=1", "B_CRT0=1"
-                )
-                abiFilters("armeabi-v7a", "arm64-v8a", "x86", "x86_64", "riscv64")
-            }
-        }
-    }
-}

native/src/AndroidManifest.xml

@@ -1,2 +0,0 @@
-<!-- This file exists only to make Android Studio happy -->
-<manifest/>