Building riscv-gnu-toolchain

I'm building the riscv-gnu-toolchain here: https://github.com/riscv-collab/riscv-gnu-toolchain like this:

 git clone https://github.com/riscv/riscv-gnu-toolchain.git cd riscv-gnu-toolchain git submodule update --init --recursive export RISCV=/opt/riscv ./configure --prefix="${RISCV}" --enable-multilib make linux

When compiling during the build of gcc I get this error:

/mnt/data/opt/riscv/sysroot/usr/include/gnu/stubs.h:8:11: fatal error:gnu/stubs-ilp32.h: No such file or directory    8 | # include <gnu/stubs-ilp32.h>      |           ^~~~~~~~~~~~~~~~~~~

I have glibc-devel.i686 and glibc-devel.x86_64 installed on CentOS Stream 8. It's a new install and all up to date. I did follow the instructions and installed the prerequisites.

I think there is something I'm missing in the prerequisites (not listed). Can someone point out what that might be?

I do need to enable multilib since this is for seL4. Here: https://docs.sel4.systems/Hardware/spike.html