Update .gitattributes

Author: maxgolov

Diff for: .gitattributes

@@ -4,6 +4,7 @@
 *.c                     text diff=cpp
 *.h                     text diff=cpp
 *.cpp                   text diff=cpp
+*.cc                    text diff=cpp
 *.cxx                   text diff=cpp
 *.hpp                   text diff=cpp