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

[kontakt at michaelstather dot com]

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

--- Comment #2 from kontakt at michaelstather dot com ---
Thank you very much, compiling works now.
But, I get linker errors. With gcc4.9.2 it works fine, but both with 5.2 and 6
I get e.g.:

C:\AVRTools4Windows\share\doc\avr-libc-1.8.1\examples\demo>make
avr-gcc -g -Wall -O2 -mmcu=atmega8    -c -o demo.o demo.c
avr-gcc -g -Wall -O2 -mmcu=atmega8  -Wl,-Map,demo.map -o demo.elf demo.o
c:/avrtools4windows/bin/../lib/gcc/avr/6.0.0/../../../../avr/bin/ld.exe: cannot
find crtatmega8.o: No such file or directory
c:/avrtools4windows/bin/../lib/gcc/avr/6.0.0/../../../../avr/bin/ld.exe: cannot
find -latmega8
collect2.exe: error: ld returned 1 exit status
Makefile:75: recipe for target 'demo.elf' failed
make: *** [demo.elf] Error 1

The file crtatmega8.o doesn't seem to exist. Other target mcus give similar
errors.