[Bug middle-end/108300] `abort()` macro cause bootstrap failure on *-w64-mingw32

[lh_mouse at 126 dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108300

--- Comment #5 from LIU Hao <lh_mouse at 126 dot com> ---
A quick and obvious fix is to add `CPPFLAGS='-DWIN32_LEAN_AND_MEAN'` when
configuring. Bootstrapped successfully on {i686,x86_64}-w64-mingw32.

I still think GCC source files should be patched.