Ensure we can always enter OSR code

When the the loop header is not the target of a back-edge,
we used to never enter the OSR code even if it's been compiled.

Test: testrunner.py --host --jit -t 570-checker-osr-locals
      (it used to get stuck, you can kill the dalvikvm to check that
      the weirdLoop was OSR-compiled)
Bug: 136743846

Change-Id: Iae55463eff92adccf9adec842e04f8ff6d9d8568
4 files changed