[Bug bootstrap/67373] Can't compile gcc snapshot for avr target with mingw

[jj at stusta dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67373

--- Comment #4 from Jonas Jelten <jj at stusta dot net> ---
It should be noted that my issue occurs on Gentoo with gcc 5.3.0, avr-libc
1.8.1 and avr binutils 2.25.1-r1.