add fsync when copy native libs

In some low probability cases, after installing apps
the device may restart without sync the storage, then
the jni libs is damaged. The file size is ok, but the
content all filled by 0x00.

Bug: 214270558
Test:
    1. adb install test.apk with jni libs
    2. Enforce restart the device
    3. check if the libs is damaged

Change-Id: Ia82cfc0d3a14c729c9ac14b367b456d65e67e058
Signed-off-by: liulvping <liulvping@xiaomi.com>