The bool data type was redefined to BOOL (4 bytes on windows).
Removed the #define and fixed some of the warnings that were uncovered
by this.
Note that the fix also disables 2 warnings :
4800 : 'type' : forcing value to bool 'true' or 'false' (performance warning)
4805: 'operation' : unsafe mix of type 'type' and type 'type' in operation

These warnings will be handled in a separate bug, as they are performance related or bogus.

Fixed to int the return type of functions that return more than 
2 distinct values.


CMakeLists.txt:
  Bug #26461: disable the C4800 and C4805 warnings temporarily
include/config-win.h:
  Bug #26461: 
   - no need for this define for Windows.
   - windows C++ compilers have a bool type
include/my_global.h:
  Bug #26461: removed bool_defined (no longer needed)
sql/handler.h:
  Bug #26461: bool functions must return boolean values
sql/mysql_priv.h:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/procedure.h:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_acl.cc:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_acl.h:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_analyse.cc:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_analyse.h:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_base.cc:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_db.cc:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_delete.cc:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_load.cc:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_parse.cc:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_prepare.cc:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.
sql/sql_update.cc:
  Bug #26461: fixed return type of functions that return more than
  2 distinct values.