Fix typo that led to compiler warning

6948b663 · Christopher Subich · 9d36be1d · 6948b663
Commit 6948b663 authored Nov 01, 2017 by Christopher Subich
--- a/src/Sorter_impl.cc
+++ b/src/Sorter_impl.cc
 #ifndef SORTER_HPP
-   #error "Sorter_impl.cc may only be #included in Sorter.hpp
+   #error "Sorter_impl.cc may only be #included in Sorter.hpp"
 #endif

 #ifndef SORTER_IMPL_CC