Rename internal types.

m-concurrent.h

@@ -721,7 +721,7 @@
   typedef struct M_C(name, _s) *M_C(name, _ptr);                        \
   typedef const struct M_C(name, _s) *M_C(name, _srcptr);               \
                                                                         \
-  typedef type M_C(name, _type_t);                                      \
+  typedef type M_C(name, _subtype_ct);                                  \
                                                                         \
   /* Define the lock strategy (multi lock) */                           \
   static inline void                                                    \