roots: trace transid_max calculation

transid_max calculations can take considerable time.  Report their
progress in more detail.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

src/bees-roots.cc

@@ -174,9 +174,9 @@ BeesRoots::transid_min()
 uint64_t
 BeesRoots::transid_max()
 {
-	BEESNOTE("Calculating transid_max");
 	uint64_t rv = 0;
 	uint64_t root = 0;
+	BEESNOTE("Calculating transid_max (" << rv << " as of root " << root << ")");
 	BEESTRACE("Calculating transid_max...");
 	do {
 		root = next_root(root);