Revert "No boost condition (#2822)" (#2828)

This reverts commit f916e64927.

utils/threadpool/wtp.cpp

@@ -31,7 +31,7 @@ using namespace std;
 #include "weightedthreadpool.h"
 
 int thecount = 0;
-std::mutex mutex;
+boost::mutex mutex;
 
 // Functor class
 struct foo
@@ -42,7 +42,7 @@ struct foo
       // simulate some work
       fData++;
 
-    // std::unique_lock lock(mutex);
+    // boost::mutex::scoped_lock lock(mutex);
     // std::cout << "foo count = " << ++thecount << " " << fData << std::endl;
   }
 
@@ -70,7 +70,7 @@ int main(int argc, char** argv)
       pool.invoke(bar, 25);
     }
 
-    std::unique_lock lock(mutex);
+    boost::mutex::scoped_lock lock(mutex);
     std::cout << "count = " << ++thecount << std::endl;
 
     // Wait until all of the queued up and in-progress work has finished