[Bug bootstrap/100731] GCC 11 fails to build using GCC 4.8 because of missing includes

[harald at gigawatt dot nl via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100731

--- Comment #1 from Harald van Dijk <harald at gigawatt dot nl> ---
The full configure line I used for reproducing this on glibc, btw:

  ../gcc-11.1.0/configure --prefix=$HOME/gcc-11.1.0-run CC=gcc-4.8.5
CXX=g++-4.8.5 --enable-languages=c,c++