Without the change when I attempt to built `nixpkgs` with weekly
`gcc-13` (it pulls in `flex` as a build input`) I am getting build
failure related to glibc mix caused by glibc loading:
...-binutils-patchelfed-ld-2.40/bin/ld: ...-xgcc-13.0.0/libexec/gcc/x86_64-unknown-linux-gnu/13.0.1/liblto_plugin.so:
error loading plugin: ...-bootstrap-tools/lib/libpthread.so.0: undefined symbol: __libc_vfork, version GLIBC_PRIVATE
The change disables LTO plugin entirely to avoid loading of `glibc` mix.
c2e14a73e6