CLEANUP: map: it seems that the map were planed to be chained

It seems that the map were planed to be chained, but obviously
it is not the case. This patch remove the struct which should
be used gor the chain

include/types/map.h

@@ -25,15 +25,7 @@
 #include <types/pattern.h>
 #include <types/sample.h>
 
-/* These structs contains a string representation of the map. These struct is
- * sorted by file. Permit to hot-add and hot-remove entries.
- *
- * "maps" is the list head. This list cotains all the mao file name identifier.
- */
-extern struct list maps;
-
 struct map_descriptor {
-	struct list list;              /* used for listing */
 	struct sample_conv *conv;      /* original converter descriptor */
 	struct pattern_head pat;       /* the pattern matching associated to the map */
 	int do_free;                   /* set if <pat> is the orignal pat and must be freed */