Windows: Fix possible crash when using longjmp and gcc 4.6

* With gcc-4.6 the option -fomit-frame-pointer is turned on per default
  even for the win32 target. This results in segfaults for any application
  using setjmp/longjmp and MSVCRT.dll on WinXP.
  See http://gcc.gnu.org/ml/gcc/2011-10/msg00351.html
* Issue reported by Lars Kanis
2 files changed