bug fix: SplitDelegateClassloader inject is not compatible with Tinker

[xiangtailiang]

tinker的从1.9.14.9版本开始，还会替换掉mBase中的mClassLoader。
com.iqiyi.android.qigsaw.core.splitload.SplitDelegateClassloader#inject的hook不彻底，只替换了mBase中的mPackageInfo里的mClassLoader，没有把mBase的mClassLoader也替换掉。

Tencent/tinker@b658362
Tinker hook的具体方法：

com.tencent.tinker.loader.NewClassLoaderInjector#doInject
  final Context baseContext = (Context) findField(app.getClass(), "mBase").get(app);
        try {
            findField(baseContext.getClass(), "mClassLoader").set(baseContext, classLoader);
        } catch (Throwable ignored) {
            // There's no mClassLoader field in ContextImpl before Android O.
            // However we should try our best to replace this field in case some
            // customized system has one.
        }
        final Object basePackageInfo = findField(baseContext.getClass(), "mPackageInfo").get(baseContext);
        findField(basePackageInfo.getClass(), "mClassLoader").set(basePackageInfo, classLoader);

而当我们使用getApplicationContext().getClassLoader()获取ClassLoader，实际上是调用了Application中的mBase.getClassLoader()。而这个mBase是frameworks/base/core/java/android/app/ContextImpl.java，里面的getClassLoader实现：

@Override
    public ClassLoader getClassLoader() {
        return mClassLoader != null ? mClassLoader : (mPackageInfo != null ? mPackageInfo.getClassLoader() : ClassLoader.getSystemClassLoader());
    }

因为mClassLoader被tinker注入了新的ClassLoader，所以会优先返回，而Qigsaw注入在mPackageInfo的ClassLoader，是无法被调用的。