Define ENOTSUP in the case where it actually is used if it isn't defined.

dtable.c

@@ -17,10 +17,10 @@
 PRIVATE dtable_t uninstalled_dtable;
 #if defined(WITH_TRACING) && defined (__x86_64)
 PRIVATE dtable_t tracing_dtable;
+#endif
 #ifndef ENOTSUP
 #	define ENOTSUP -1
 #endif
-#endif
 
 /** Head of the list of temporary dtables.  Protected by initialize_lock. */
 PRIVATE InitializingDtable *temporary_dtables;