Fix a warning building DM using ninja on Mac.

dm/DMTask.cpp

Index: dm/DMTask.cpp
diff --git a/dm/DMTask.cpp b/dm/DMTask.cpp
index 9b463f90031b555c27f5470c0c7fb1a33c11baa8..ba74a5f4098c0547d73bc5144062c20725e0aa92 100644
--- a/dm/DMTask.cpp
+++ b/dm/DMTask.cpp
@@ -12,7 +12,10 @@ Task::Task(Reporter* reporter, TaskRunner* taskRunner)
     fReporter->start();
 }
 
-Task::Task(const Task& that) : fReporter(that.fReporter), fTaskRunner(that.fTaskRunner) {
+Task::Task(const Task& that)
+    : INHERITED(that)
+    , fReporter(that.fReporter)
+    , fTaskRunner(that.fTaskRunner) {
     fReporter->start();
 }