add complete java side of sqlite implementation

Mostly taken from https://www.sqlite.org/android which is forked from
AOSPs implementation

src/api-impl/android/database/sqlite/SQLiteCustomFunction.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+** Modified to support SQLite extensions by the SQLite developers: 
+** sqlite-dev@sqlite.org.
+*/
+
+package android.database.sqlite;
+
+/**
+ * Describes a custom SQL function.
+ *
+ * @hide
+ */
+public final class SQLiteCustomFunction {
+	public final String name;
+	public final int numArgs;
+	public final SQLiteDatabase.CustomFunction callback;
+
+	/**
+	 * Create custom function.
+	 *
+	 * @param name The name of the sqlite3 function.
+	 * @param numArgs The number of arguments for the function, or -1 to
+	 * support any number of arguments.
+	 * @param callback The callback to invoke when the function is executed.
+	 */
+	public SQLiteCustomFunction(String name, int numArgs,
+			SQLiteDatabase.CustomFunction callback) {
+		if (name == null) {
+			throw new IllegalArgumentException("name must not be null.");
+		}
+
+		this.name = name;
+		this.numArgs = numArgs;
+		this.callback = callback;
+	}
+
+	// Called from native.
+	@SuppressWarnings("unused")
+	private void dispatchCallback(String[] args) {
+		callback.callback(args);
+	}
+}