make: Entering directory '/home/buildroot/build/instance-0/buildroot'

Your Buildroot configuration needs a compiler capable of building 32 bits binaries.
If you're running a Debian/Ubuntu distribution, install the g++-multilib package.
For other distributions, refer to their documentation.
support/dependencies/dependencies.mk:22: recipe for target 'core-dependencies' failed
make: *** [core-dependencies] Error 1
make: Leaving directory '/home/buildroot/build/instance-0/buildroot'