This tests that ApfGenerator knows how to optimally encode positive and
negative immediates of various sizes.
Equivalent tests will follow for LDDW and STDW.
Change-Id: Ia904aecb155c78569e3cf32a2431570281570481
Bug: 73804303
Test: runtest tests/net/java/android/net/apf/ApfTest.java
(cherry picked from commit 18050000d7)