Produce warnings of wrong cast of strings to signed/unsigned.
Don't block not resolved IP's if DNS server is down (Bug #8467)
Fix compiler problems with MinGW (Bug #8872)


configure.in:
  Fix compiler problems with MinGW (Bug #8872)
include/config-win.h:
  Fix compiler problems with MinGW (Bug #8872)
include/my_global.h:
  Fix compiler problems with MinGW (Bug #8872)
mysql-test/r/cast.result:
  Test for cast to signed/unsigned outside of range (Bug #7036)
mysql-test/t/cast.test:
  Test for cast to signed/unsigned outside of range (Bug #7036)
mysys/default.c:
  Cleanup (combine identical code). 
  Done mainly by Jani
sql/field.h:
  Added cast_to_int_type() to ensure that enums are casted as numbers
sql/hostname.cc:
  Don't block not resolved IP's if DNS server is down (Bug #8467)
sql/item.h:
  Added cast_to_int_type() to ensure that enums are casted as numbers
sql/item_func.cc:
  CAST(string_argument AS UNSIGNED) didn't work for big integers above the
  signed range. (Bug #7036)
  Produce warnings of wrong cast of strings to signed/unsigned
sql/item_func.h:
  CAST(string_argument AS UNSIGNED) didn't work for big integers above the
  signed range. (Bug #7036)