Fixes after last merge of MySQL 5.1

- INSERT with RAND() doesn't require row based logging again
- Some bugs fixed in opt_range() where we table->key_read was wrongly used



.bzrignore:
  Ignore new xtstat binary
mysql-test/r/index_merge_myisam.result:
  Update results (old result was wrong)
mysql-test/suite/binlog/r/binlog_stm_binlog.result:
  Added drop table first
mysql-test/suite/binlog/r/binlog_stm_unsafe_warning.result:
  Added test for when RAND() requires row based logging
mysql-test/suite/binlog/t/binlog_stm_binlog.test:
  Added drop table first
mysql-test/suite/binlog/t/binlog_stm_unsafe_warning.test:
  Added test for when RAND() requires row based logging
scripts/make_binary_distribution.sh:
  Removed type from last commit
sql/item_create.cc:
  Don't require row based logging when using RAND() with INSERT
sql/opt_range.cc:
  Revert wrong patch from Oracle:
  - As QUICK_RANGE_SELECT uses it's own 'file' handler to the tables, one can't use 'table->key_read' as a flag to detect if index only read (keyread) is used or not
  - Don't set keyread if keyread is already enabled
  - Don't disable key read, if we didn't enable it ourselves
  - Simplify code (and ensure that we do proper cleanup of index only read)
sql/opt_range.h:
  Added flags to detect if the range optimizer enabled index only read (key read) or not
sql/opt_sum.cc:
  Use our more optimized macros
sql/sql_lex.h:
  Added 'readable' function to check if we are in a sub query function or not (not normal query or sub query in FROM clause)
sql/sql_select.cc:
  Use our more optimized keyread macros
  Added ASSERTS early
  Simplify code on eliminate_item_equal()
  Fixed that substitute_for_best_equal_field() doesn't core dump in case of out of memory conditions.
  Removed not needed test for 'field->maybe_null()'
  Replaced master_unit()->item with is_subquery_function() (More readable)
sql/sql_update.cc:
  Use our more optimized keyread macros
sql/table.cc:
  Use our more optimized keyread macros
sql/table.h:
  Use separate functions to enable/disable Index only reads
  - Safer, more readable, better logging and faster.

sql/opt_range.h

@@ -280,6 +280,8 @@ class QUICK_RANGE_SELECT : public QUICK_SELECT_I
 {
 protected:
   bool next,dont_free,in_ror_merged_scan;
+  /* true if we enabled key only reads */
+  bool doing_key_read;
 public:
   int error;
 protected:
@@ -623,6 +625,8 @@ private:
   bool have_min;         /* Specify whether we are computing */
   bool have_max;         /*   a MIN, a MAX, or both.         */
   bool seen_first_key;   /* Denotes whether the first key was retrieved.*/
+  bool doing_key_read;   /* true if we enabled key only reads */
+
   KEY_PART_INFO *min_max_arg_part; /* The keypart of the only argument field */
                                    /* of all MIN/MAX functions.              */
   uint min_max_arg_len;  /* The length of the MIN/MAX argument field */