Merge with 5.1-microseconds

A lot of small fixes and new test cases.

client/mysqlbinlog.cc:
  Cast removed
client/mysqltest.cc:
  Added missing DBUG_RETURN
include/my_pthread.h:
  set_timespec_time_nsec() now only takes one argument
mysql-test/t/date_formats.test:
  Remove --disable_ps_protocl as now also ps supports microseconds
mysys/my_uuid.c:
  Changed to use my_interval_timer() instead of my_getsystime()
mysys/waiting_threads.c:
  Changed to use my_hrtime()
sql/field.h:
  Added bool special_const_compare() for fields that may convert values before compare (like year)
sql/field_conv.cc:
  Added test to get optimal copying of identical temporal values.
sql/item.cc:
  Return that item_int is equal if it's positive, even if unsigned flag is different.
  Fixed Item_cache_str::save_in_field() to have identical null check as other similar functions
  Added proper NULL check to Item_cache_int::save_in_field()
sql/item_cmpfunc.cc:
  Don't call convert_constant_item() if there is nothing that is worth converting.
  Simplified test when years should be converted
sql/item_sum.cc:
  Mark cache values in Item_sum_hybrid as not constants to ensure they are not replaced by other cache values in compare_datetime()
sql/item_timefunc.cc:
  Changed sec_to_time() to take a my_decimal argument to ensure we don't loose any sub seconds.
  Added Item_temporal_func::get_time() (This simplifies some things)
sql/mysql_priv.h:
  Added Lazy_string_decimal()
sql/mysqld.cc:
  Added my_decimal constants max_seconds_for_time_type, time_second_part_factor
sql/table.cc:
  Changed expr_arena to be of type CONVENTIONAL_EXECUTION to ensure that we don't loose any items that are created by fix_fields()
sql/tztime.cc:
  TIME_to_gmt_sec() now sets *in_dst_time_gap in case of errors
  This is needed to be able to detect if timestamp is 0
storage/maria/lockman.c:
  Changed from my_getsystime() to set_timespec_time_nsec()
storage/maria/ma_loghandler.c:
  Changed from my_getsystime() to my_hrtime()
storage/maria/ma_recovery.c:
  Changed from my_getsystime() to mmicrosecond_interval_timer()
storage/maria/unittest/trnman-t.c:
  Changed from my_getsystime() to mmicrosecond_interval_timer()
storage/xtradb/handler/ha_innodb.cc:
  Added support for new time,datetime and timestamp
unittest/mysys/thr_template.c:
  my_getsystime() -> my_interval_timer()
unittest/mysys/waiting_threads-t.c:
  my_getsystime() -> my_interval_timer()

sql/sql_class.cc

@@ -663,7 +663,7 @@ THD::THD()
               /* statement id */ 0),
    Open_tables_state(refresh_version), rli_fake(0),
    lock_id(&main_lock_id),
-   user_time(0), in_sub_stmt(0),
+   in_sub_stmt(0),
    sql_log_bin_toplevel(false),
    binlog_table_maps(0), binlog_flags(0UL),
    table_map_for_update(0),
@@ -705,7 +705,7 @@ THD::THD()
   main_security_ctx.init();
   security_ctx= &main_security_ctx;
   some_tables_deleted=no_errors=password= 0;
-  query_start_used= 0;
+  query_start_used= query_start_sec_part_used= 0;
   count_cuted_fields= CHECK_FIELD_IGNORE;
   killed= NOT_KILLED;
   col_access=0;
@@ -722,7 +722,7 @@ THD::THD()
 #endif
   // Must be reset to handle error with THD's created for init of mysqld
   lex->current_select= 0;
-  start_time=(time_t) 0;
+  user_time.val= start_time= start_time_sec_part= 0;
   start_utime= prior_thr_create_utime= 0L;
   utime_after_lock= 0L;
   current_linfo =  0;
@@ -986,7 +986,6 @@ void THD::update_stats(void)
 
 void THD::update_all_stats()
 {
-  time_t save_time;
   ulonglong end_cpu_time, end_utime;
   double busy_time, cpu_time;
 
@@ -995,8 +994,8 @@ void THD::update_all_stats()
     return;
 
   end_cpu_time= my_getcputime();
-  end_utime=    my_micro_time_and_time(&save_time);
-  busy_time= (end_utime - start_utime)  / 1000000.0;
+  end_utime=    microsecond_interval_timer();
+  busy_time= (end_utime - start_utime) / 1000000.0;
   cpu_time=  (end_cpu_time - start_cpu_time) / 10000000.0;
   /* In case there are bad values, 2629743 is the #seconds in a month. */
   if (cpu_time > 2629743.0)
@@ -1004,7 +1003,8 @@ void THD::update_all_stats()
   status_var_add(status_var.cpu_time, cpu_time);
   status_var_add(status_var.busy_time, busy_time);
 
-  update_global_user_stats(this, TRUE, save_time);
+  update_global_user_stats(this, TRUE, my_time(0));
+  // Has to be updated after update_global_user_stats()
   userstat_running= 0;
 }
 
@@ -2564,6 +2564,7 @@ int select_max_min_finder_subselect::send_data(List<Item> &items)
         op= &select_max_min_finder_subselect::cmp_decimal;
         break;
       case ROW_RESULT:
+      case TIME_RESULT:
       case IMPOSSIBLE_RESULT:
         // This case should never be choosen
 	DBUG_ASSERT(0);