Make SQLiteGlobal.initialize() static initializer

Author: John-He-928

android/wcdb/src/com/tencent/wcdb/database/SQLiteGlobal.java

@@ -79,7 +79,14 @@ public final class SQLiteGlobal {
     // See [JLS 12.4.1](http://docs.oracle.com/javase/specs/jls/se7/html/jls-12.html#jls-12.4.1)
     public static void loadLib() {}
     public static void initialize() {
-        nativeInitialize(defaultPageSize);
+        Initializer.init();
+    }
+
+    private static class Initializer {
+        static {
+            nativeInitialize(defaultPageSize);
+        }
+        static void init() {}
     }
 
     private SQLiteGlobal() {}
@@ -99,7 +106,7 @@ public static int releaseMemory() {
  * Probe class to detect whether "libwcdb.so" is loaded.
  * It's set to true in JNI initialization routine.
  */
-class WCDBInitializationProbe {
+final class WCDBInitializationProbe {
     static boolean libLoaded = false;
     static volatile long apiEnv = 0L;
     private WCDBInitializationProbe() {}