Fixed runningOnValgrind on OSX

[simoatze]

@jprotze I fixed the driver for OSX since it was using the wrong library extension. Also I fix the runninOnValgrind function, however now it does not report any false alarm but it does not catch any racy. I verified that the "AnnotateHappens..." get called correctly but I can't figure out why on OSX it does not find any race.

[simoatze]

@jprotze With or without Archer is not working on OSX. I can't figure out if it's a Archer or a Tsan problem.

[jprotze]

Are the races detected, if you don't link the Archer runtime library?

[simoatze]

@jprotze I need to double check, but if I remember correctly when I don't link with Archer the races are detected but we get false positives on the tests with no races. If we link with Archer we get no false positives but not races are detected.