Logger: Print solve number along with candidate solution for debug info

While solving the timestamp problem in log reader, print the solve
number for a candidate solution. This can be helpful to dig into the
details of a particular solve.

Change-Id: I941ae4019039898eae3ff9638e46ae8587ced6b2
Signed-off-by: James Kuszmaul <james.kuszmaul@bluerivertech.com>
diff --git a/aos/network/multinode_timestamp_filter.cc b/aos/network/multinode_timestamp_filter.cc
index 5476f01..91d7854 100644
--- a/aos/network/multinode_timestamp_filter.cc
+++ b/aos/network/multinode_timestamp_filter.cc
@@ -2933,7 +2933,8 @@
     }
 
     if (VLOG_IS_ON(1)) {
-      VLOG(1) << "Candidate solution for node " << node_a_index << " is";
+      VLOG(1) << "Candidate solution for node " << node_a_index
+              << " on solve number " << solver.my_solve_number() << " is";
       for (size_t i = 0; i < solution.size(); ++i) {
         VLOG(1) << "  " << solution[i];
       }