Reduce the number of calls to Jit::AddSamples.

The method is called for every invoke which is expensive.
Add samples, but don't check the consequences every time.

This reduces its cost from 3.5% to 1% (maps on device).

Test: ./art/test.py -b -r --host --64
Change-Id: Ie90da905d067b5d85a3c494c7c9af81b24dc8135