Fix for BUG#2477 "Slave stop with error after master reboot if use HEAP tables":

when we open the HEAP table for the first time since server restart,
in hp_open(), we set a flag to propagate this info to the handler level
which then writes a DELETE FROM this_heap_table to the binlog.
It is not a perfect solution for the bug, because between the server start and 
the first open of the table, the slave still had old data in his table so
a SELECT on the slave may show wrong content. But if there is a --init-file
to populate the HEAP table on master as startup, then this is a safe fix
(I'll put a note about init-file in the HEAP section of the manual).


heap/hp_info.c:
  new info variable implicit_emptied
heap/hp_open.c:
  If this is the first open of the HEAP table, it means it is empty,
  so we mark it.
include/heap.h:
  new variables implicit_emptied
  (we need one in HEAPINFO for the hp_info() call).
sql/ha_heap.cc:
  report info to upper level
sql/handler.h:
  new info 'implicit_emptied' in the handler level; only HEAP uses it.
sql/sql_base.cc:
  When a HEAP table is opened for the first time, write a DELETE FROM to the binlog,
  for replication and mysqlbinlog|mysql.
  Monty: I added the
  entry->file->implicit_emptied= 0;

sql/handler.h

@@ -213,6 +213,7 @@ public:
   uint raid_type,raid_chunks;
   FT_INFO *ft_handler;
   bool  auto_increment_column_changed;
+  bool implicit_emptied;                /* Can be !=0 only if HEAP */
 
   handler(TABLE *table_arg) :table(table_arg),
     ref(0), data_file_length(0), max_data_file_length(0), index_file_length(0),
@@ -221,7 +222,7 @@ public:
     create_time(0), check_time(0), update_time(0),
     key_used_on_scan(MAX_KEY), active_index(MAX_REF_PARTS),
     ref_length(sizeof(my_off_t)), block_size(0),
-    raid_type(0), ft_handler(0)
+    raid_type(0), ft_handler(0), implicit_emptied(0)
     {}
   virtual ~handler(void) {}
   int ha_open(const char *name, int mode, int test_if_locked);