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


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665279 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/cpp/src/concurrency/Mutex.h b/lib/cpp/src/concurrency/Mutex.h
index 72f7525..b19e3c5 100644
--- a/lib/cpp/src/concurrency/Mutex.h
+++ b/lib/cpp/src/concurrency/Mutex.h
@@ -18,7 +18,7 @@
 class Mutex {
  public:
   Mutex();
-  virtual ~Mutex() {}
+  virtual ~Mutex();
   virtual void lock() const;
   virtual bool trylock() const;
   virtual void unlock() const;
@@ -31,7 +31,7 @@
 class ReadWriteMutex {
 public:
   ReadWriteMutex();
-  virtual ~ReadWriteMutex() {}
+  virtual ~ReadWriteMutex();
 
   // these get the lock and block until it is done successfully
   virtual void acquireRead() const;