tal: rename tal_len to tal_bytelen.

I had a bug caused by using tal_len instead of tal_count: let's make
it explicit. @jb55 commented "ha. I always forget which one does which... Ack"
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/tal/tal.c

@@ -656,7 +656,7 @@ const char *tal_name(const tal_t *t)
 	return n->name;
 }
 
-size_t tal_len(const tal_t *ptr)
+size_t tal_bytelen(const tal_t *ptr)
 {
 	struct length *l;
 

ccan/tal/tal.h

@@ -310,16 +310,16 @@ const char *tal_name(const tal_t *ptr);
  * Returns 0 if @ptr has no length property or is NULL, but be aware
  * that that is also a valid size!
  */
-#define tal_count(p) (tal_len(p) / sizeof(*p))
+#define tal_count(p) (tal_bytelen(p) / sizeof(*p))
 
 /**
- * tal_len - get the count of bytes in a tal_arr.
+ * tal_bytelen - get the count of bytes in a tal_arr.
  * @ptr: The tal allocated object array (or NULL)
  *
  * Returns 0 if @ptr has no length property or NULL, but be aware that that is
  * also a valid size!
  */
-size_t tal_len(const tal_t *ptr);
+size_t tal_bytelen(const tal_t *ptr);
 
 /**
  * tal_first - get the first immediate tal object child.

ccan/tal/test/run-count.c

@@ -46,7 +46,7 @@ int main(void)
 	plan_tests(2 + 19 * 3);
 
 	p1 = NULL;
-	ok1(tal_len(p1) == 0);
+	ok1(tal_bytelen(p1) == 0);
 	ok1(tal_count(p1) == 0);
 
 	for (i = 0; i < 3; i++) {