Recent changes to newlib Makefiles break cygwin

[Christopher Faylor]

I'm surprised that no one attempted to build cygwin after the recent
huge change to newlib configury.

Unless I'm missing something, vfprintf.o is being miscompiled, resulting
in this error:
/cygnus/build/win32/i686-pc-cygwin/newlib/libc/libc.a(vfiprintf.o)(.text+0x2ad):vfprintf.c: undefined reference to `__imp____mb_cur_max'

This is due to the fact that vfprintf.o is, AFAICT, the only object file
in the newlib/libc/stdio directory that is not compiled with the
-D_COMPILING_NEWLIB option (among other options).

Could we get this fixed, please?  Either that or tell me what I'm doing
wrong...

cgf