Fix *_ctx_new and *_ctx_free implementations

They both will only alloc and free the internal *_ctx structs. Get rid
of the void * argument for new and only pass arg to *_free instead of
the whole lc_*_ctx struct.

auth_poly1305.c

@@ -154,11 +154,12 @@ poly1305_auth(const uint8_t *key, size_t keylen, uint8_t *out, size_t *outlen,
 }
 
 static void *
-poly1305_ctx_new(const void *arg)
+poly1305_ctx_new(void)
 {
 	return malloc(sizeof(struct poly1305_ctx));
 }
 
+
 static struct lc_auth_impl	poly1305_impl = {
 	.init = &poly1305_init,
 	.update = &poly1305_update,