CondVar::SignalAll was broken, leading to deadlocks on Windows builds.

http://code.google.com/p/leveldb/issues/detail?id=149

src/cpp/leveldb/port/port_win.cc

@@ -109,12 +109,10 @@ void CondVar::Signal() {
 
 void CondVar::SignalAll() {
   wait_mtx_.Lock();
-  for(long i = 0; i < waiting_; ++i) {
-    ::ReleaseSemaphore(sem1_, 1, NULL);
-    while(waiting_ > 0) {
-      --waiting_;
-      ::WaitForSingleObject(sem2_, INFINITE);
-    }
+  ::ReleaseSemaphore(sem1_, waiting_, NULL);
+  while(waiting_ > 0) {
+    --waiting_;
+    ::WaitForSingleObject(sem2_, INFINITE);
   }
   wait_mtx_.Unlock();
 }