Weak symbols on MacOS

[simoatze]

@jprotze I made a branch mac_osx, I tried to deal with the weak symbols and currently, it passes most of the tests except does not catch some races. One thing that I noticed is that these tests sometimes randomly passes most of the time they don't.
If you take a look to ompt-tsan.cpp, you can see how I dealt with the weak symbols, if that's ok I am not sure what could other problems be.

[jprotze]

Can you add a list of the tests that fail on Mac?

[simoatze]

Sometimes are only these:

races/critical-unrelated.c
races/lock-nested-unrelated.c
races/task-dependency.c
races/task-taskwait-nested.c

and sometimes are more:

races/critical-unrelated.c
races/lock-nested-unrelated.c
races/lock-unrelated.c
races/parallel-simple.c
races/task-dependency.c
races/task-taskwait-nested.c
races/task-two.c

[simoatze]

@jprotze Did you give a try to this?

[jprotze]

I had a quick look, but didn't have an idea why these might fail.
I try to have a closer look during the flight back from SC.