Convert C++/C99 style comments to C89

I'm only doing this once and I'll probably regress later.

Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>
diff --git a/src/cborjson.h b/src/cborjson.h
index 58c4cae..8ff27b9 100644
--- a/src/cborjson.h
+++ b/src/cborjson.h
@@ -58,5 +58,5 @@
 }
 #endif
 
-#endif // CBORJSON_H
+#endif /* CBORJSON_H */