DO NOT MERGE. Fix building support library using gradle in AOSP.

Update build.gradle to point to API 25 Android Jar.

Additionally, update the PREUPLOAD.cfg to point to
the new location of checkstyle

Bug: 34875427
Test: Android studio is now happy and shows no errors.
Change-Id: Ie873274869cb7d31e86670450ad6e09c61c2aee8
2 files changed