If you are on an amd64 installation, you can try to install the package libc6-dev-i386. This helped me solve the same issue you encountered while trying to compile smm from i8kutils.

using this command (or a similar one, depending on your OS)

apt-get install libc6-dev-i386

Needed to add --with-float=hard to the configure line.

This is because MULTIARCH_DIRNAME is defined based on the with-float configuration option

MULTIARCH_DIRNAME = $(call if_multiarch,arm$(ARM_EB)-linux-gnueabi(filter hard,$(with_float)),hf))

As pointed out by the kind fellows at gcc

Followed another link which helped me to solve the issue.
libc6-dev-i386 was not installed in my system. After installing with this command in my Ubuntu the errors were gone.

sudo apt-get install g++-multilib

Answer from ubuntu link for reference

To compile 32 bit binaries on 64 bit Linux version, you have to Install libx32gcc development package and 32 bit GNU C Library

try this

sudo apt-get install libx32gcc-4.8-dev

and

sudo apt-get install libc6-dev-i386

I had similar problem with compiling gcc-8.2. I tried to do as described here with reinstalling:

sudo apt-get --reinstall install libc6 libc6-dev

After that I was locating all missing headers:

find / -name cdefs.h 

and copying them to /usr/include: those steps allowed only to move forward but I still didn't manage to completely build gcc.

The best solution I found is to download compiled version of gcc-8.1 from: https://solarianprogrammer.com/2017/12/07/raspberry-pi-raspbian-compiling-gcc/