[buddy]

Tag functions with attributes pure, const, or noreturn.

* src/bdd.h (__purefn, __constfn, __noreturnfn): Define
new macros.
* src/bdd.h, src/bddio.c, src/bvec.h, src/imatrix.h: Use them
to tag many functions as suggested by -Wsuggest-attribute=pure,
-Wsuggest-attribute=const, -Wsuggest-attribute=noreturn.

buddy/src/bddio.c

@@ -578,7 +578,7 @@ static void loadhash_add(int key, int data)
    lh_table[pos].data = data;
 }
 
-
+__purefn
 static int loadhash_get(int key)
 {
    int hash = lh_table[key % lh_nodenum].first;