Change some my_bool in C++ classes and a few functions to bool to detect wrong usage of bool/my_bool.
Fix some bugs where we stored values other than 0 or 1 in my_bool
Fixed some compiler warnings


client/mysql.cc:
  Changed interrupted_query from my_bool to int, as we stored 2 in it.
client/mysqladmin.cc:
  Changed return variable type to same type as function value type
client/mysqltest.cc:
  Changed 'found' to int as we store other values than 0 or 1 into it
  Changed type for parameter of set_reconnect() to match usage.
extra/libevent/evbuffer.c:
  Added __attribute__((unused))
extra/libevent/event.c:
  Added __attribute__((unused))
extra/libevent/signal.c:
  Added __attribute__((unused))
sql/event_data_objects.h:
  my_bool -> bool
sql/event_db_repository.cc:
  my_bool -> bool
sql/event_db_repository.h:
  my_bool -> bool
sql/event_parse_data.h:
  my_bool -> bool
sql/events.cc:
  my_bool -> bool
sql/events.h:
  my_bool -> bool
sql/field.cc:
  my_bool -> bool
sql/field.h:
  my_bool -> bool
sql/hash_filo.h:
  my_bool -> bool
sql/item.cc:
  my_bool -> bool
sql/item.h:
  my_bool -> bool
sql/item_cmpfunc.h:
  my_bool -> bool
  Changed result_for_null_param from my_bool to int as we stored -1 in it.
sql/item_func.cc:
  my_bool -> bool
  Modified udf wrapper functions so that the UDF functions would continue to use my_bool. (To keep compatibility with UDF:s)
sql/item_func.h:
  my_bool -> bool
sql/item_subselect.h:
  my_bool -> bool
sql/item_sum.cc:
  Modified udf wrapper functions so that the UDF functions would continue to use my_bool. (To keep compatibility with UDF:s)
sql/parse_file.h:
  my_bool -> bool
sql/rpl_mi.h:
  my_bool -> bool
sql/sp_rcontext.h:
  my_bool -> bool
sql/sql_analyse.h:
  my_bool -> bool
sql/sql_base.cc:
  Change some assignments so that we don't initialize bool variables with int's.
sql/sql_bitmap.h:
  my_bool -> bool
sql/sql_cache.cc:
  my_bool -> bool
sql/sql_cache.h:
  my_bool -> bool
sql/sql_class.h:
  my_bool -> bool
sql/sql_insert.cc:
  Change some assignments so that we don't initialize bool variables with int's.
sql/sql_prepare.cc:
  my_bool -> bool
sql/table.h:
  my_bool -> bool
storage/maria/ma_check.c:
  Removed duplicate assignment
strings/decimal.c:
  Fixed wrong variable usage.
  Don't do complex arithmetic on bool when simple works.