Revert^4 "JIT JNI stubs."

The original CL,
    https://android-review.googlesource.com/513417 ,
has a bug fixed in the Revert^2,
    https://android-review.googlesource.com/550579 ,
and this Revert^4 adds two more fixes:
    - fix obsolete native method getting interpreter
      entrypoint in 980-redefine-object,
    - fix random JIT GC flakiness in 667-jit-jni-stub.

Test: testrunner.py --host --prebuild --no-relocate \
      --no-image --jit -t 980-redefine-object
Bug: 65574695
Bug: 69843562

This reverts commit 056d7756.

Change-Id: Ic778686168b90e29816fd526e23141dcbe5ea880