Revert^2 "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).

This reverts commit 0402f4b0
and fixes 667-jit-jni-stub which relied on being able to set
the sample count to exactly one below the compilation threshold,
and then expected the compilation to happen on the next sample.

Test: ./art/test.py -b --host -r --ndebug
Test: ./art/test.py -b -r -t 570
Change-Id: I99c6d03f565f17fe6539ed89632d8f8bbda68107