Revision 665279

THRIFT: Mutex and ReadWriteMutex leaked memory, now they don't

Summary: also added myself to CONTRIBUTORS.

Reviewed By: marc

Test Plan: the following program no longer leaks memory (valgrind):

int main(int argc, char **argv){
  Mutex mu;
  mu.lock();
  mu.unlock();
}

Revert Plan: ok

Notes: this is kind of important