merge of 5.1-main into 5.1-maria. Myisam->Maria change propagation will follow.

There were so many changes into mtr (this is the new mtr coming) that I rather
copied mtr from 6.0-main here (at least this one knows how to run Maria tests).
I also fixed suite/maria tests to be accepted by the new mtr.

mysys/thr_mutex.c:
  adding DBUG_PRINT here, so that we can locate where the warning is issued.

mysql-test/include/wait_until_connected_again.inc

@@ -8,10 +8,13 @@
 --disable_result_log
 --disable_query_log
 let $counter= 5000;
-let $mysql_errno= 1;
+let $mysql_errno= 9999;
 while ($mysql_errno)
 {
-  --error 0,2002,2003,2006,1053
+  # Strangely enough, the server might return "Too many connections"
+  # while being shutdown, thus 1040 is an "allowed" error
+  # See BUG#36228
+  --error 0,1040,1053,2002,2003,2006,2013
   show status;
 
   dec $counter;