Rename macros:

* CAT* --> M_C*

m-string.h

@@ -633,7 +633,7 @@ string_in_str(string_t v, FILE *f)
 }
 
 #define STRING_SPLIT(name, oplist, type_oplist)                         \
-  static inline void CAT(name, _split)(M_GET_TYPE oplist cont,          \
+  static inline void M_C(name, _split)(M_GET_TYPE oplist cont,          \
                                    const string_t str, const char sep)  \
   {                                                                     \
     size_t begin = 0;                                                   \