fix typo (#3108)

diff --git a/heron/common/src/cpp/threads/pcqueue.h b/heron/common/src/cpp/threads/pcqueue.h
index 2a9cb01..7d071d9 100644
--- a/heron/common/src/cpp/threads/pcqueue.h
+++ b/heron/common/src/cpp/threads/pcqueue.h
@@ -19,7 +19,7 @@
 
 ////////////////////////////////////////////////////////////////////
 //
-// This file consists of ciass definition of a producer consumer queue
+// This file consists of class definition of a producer consumer queue
 //
 /////////////////////////////////////////////////////////////////////