Use overloading instead of default values

As we are getting ready to add the send boot UUID everywhere, that will
require a UUID as an argument to all the Send methods with a default
that is event_loop_->boot_uuid().  That doesn't work.  Instead, use
overloading to achieve the same purpose.

There are few call sites for all of these, so it isn't hard to change
them all.

Change-Id: Id1e17bbef2e63c72fa6ad2b038c69d452610e86e
diff --git a/aos/ipc_lib/queue_racer.cc b/aos/ipc_lib/queue_racer.cc
index 5b3d88b..afd4135 100644
--- a/aos/ipc_lib/queue_racer.cc
+++ b/aos/ipc_lib/queue_racer.cc
@@ -177,7 +177,9 @@
         }
 
         ++started_writes_;
-        sender.Send(sizeof(ThreadPlusCount));
+        sender.Send(sizeof(ThreadPlusCount), aos::monotonic_clock::min_time,
+                    aos::realtime_clock::min_time, 0xffffffff,
+                    nullptr, nullptr, nullptr);
         // Blank out the new scratch buffer, to catch other people using it.
         {
           char *const new_data = static_cast<char *>(sender.Data()) +
@@ -261,10 +263,10 @@
 
   for (uint64_t i = initial_i;
        i < (1 + write_wrap_count) * num_messages_ * num_threads_; ++i) {
-    ::aos::monotonic_clock::time_point monotonic_sent_time;
-    ::aos::realtime_clock::time_point realtime_sent_time;
-    ::aos::monotonic_clock::time_point monotonic_remote_time;
-    ::aos::realtime_clock::time_point realtime_remote_time;
+    monotonic_clock::time_point monotonic_sent_time;
+    realtime_clock::time_point realtime_sent_time;
+    monotonic_clock::time_point monotonic_remote_time;
+    realtime_clock::time_point realtime_remote_time;
     uint32_t remote_queue_index;
     size_t length;
     char read_data[1024];