cmListFileContext: Implement EqualityComparable.

Source/cmListFileCache.cxx

@@ -440,3 +440,13 @@ bool operator<(const cmListFileContext& lhs, const cmListFileContext& rhs)
     }
   return lhs.FilePath < rhs.FilePath;
 }
+
+bool operator==(const cmListFileContext& lhs, const cmListFileContext& rhs)
+{
+  return lhs.Line == rhs.Line && lhs.FilePath == rhs.FilePath;
+}
+
+bool operator!=(const cmListFileContext& lhs, const cmListFileContext& rhs)
+{
+  return !(lhs == rhs);
+}

Source/cmListFileCache.h

@@ -63,6 +63,8 @@ struct cmListFileContext
 
 std::ostream& operator<<(std::ostream&, cmListFileContext const&);
 bool operator<(const cmListFileContext& lhs, const cmListFileContext& rhs);
+bool operator==(cmListFileContext const& lhs, cmListFileContext const& rhs);
+bool operator!=(cmListFileContext const& lhs, cmListFileContext const& rhs);
 
 struct cmListFileFunction: public cmListFileContext
 {