[veridex] Add a --target-sdk-version to avoid false positives.

1) Recognize Build.VERSION.SDK_INT in flow analysis
2) Recognize simple if patterns.

bug: 79404565
bug: 77513322
Test: m

(cherry picked from commit 2a843c81e61128d2c1723c064786f8b7193c62f5)

Change-Id: I0327f2468ce620ed4dc218bda5a3fc16f285cb7b
4 files changed