Mark smartlist_bsearch as taking a const list.

It does not modify the actual list.

src/common/container.c

@@ -628,7 +628,7 @@ smartlist_uniq(smartlist_t *sl,
  * less than member, and greater than 0 if key is greater then member.
  */
 void *
-smartlist_bsearch(smartlist_t *sl, const void *key,
+smartlist_bsearch(const smartlist_t *sl, const void *key,
                   int (*compare)(const void *key, const void **member))
 {
   int found, idx;

src/common/container.h

@@ -120,7 +120,7 @@ const uint8_t *smartlist_get_most_frequent_digest256(smartlist_t *sl);
 void smartlist_uniq_strings(smartlist_t *sl);
 void smartlist_uniq_digests(smartlist_t *sl);
 void smartlist_uniq_digests256(smartlist_t *sl);
-void *smartlist_bsearch(smartlist_t *sl, const void *key,
+void *smartlist_bsearch(const smartlist_t *sl, const void *key,
                         int (*compare)(const void *key, const void **member));
 int smartlist_bsearch_idx(const smartlist_t *sl, const void *key,
                           int (*compare)(const void *key, const void **member),