Fix a number of problems in the test suite (no code bugs):

- mysql-test-run.pl --valgrind complains when all tests succeed.

 - perfschema.all_instances fail on non-linux, where ENABLE_TEMP_POOL
   is not set and therefore BITMAP mutex is not used.

 - MDEV-132: main.mysqldump fails because it depends on exact size of stdio
   buffers.

 - MDEV-99: rpl.rpl_cant_read_event_incident fails due to a race where the
   slave manages to connect while the test case is in the middle of setting up
   the master, causing the slave to replicate extra/wrong events.

 - MDEV-133: rpl.rpl_rotate_purge_deadlock fails because it issues a
   DEBUG_SYNC SIGNAL immediately followed by RESET; this means that sometimes
   the intended receipient has no time to see the signal before it is cleared
   by the RESET, causing wait to timeout.

mysql-test/mysql-test-run.pl

@@ -584,6 +584,7 @@ sub main {
     }
     mtr_report_test($tinfo);
     push @$completed, $tinfo;
+    ++$num_tests
   }
 
   mtr_print_line();
@@ -599,7 +600,8 @@ sub main {
 
   if ( @$completed != $num_tests)
   {
-    mtr_error("Not all tests completed");
+    mtr_error("Not all tests completed (only ". scalar(@$completed) .
+              " of $num_tests)");
   }
 
   remove_vardir_subs() if $opt_clean_vardir;