Having lib, lib32, and lib64... it's better to be friendly to such use case.
IIUC, here are some info:
- they (will) use <host_alias>-gpgrt-config script
- in configure, CC is cc or gcc with no <host_alias>- prefix
(I feel the terminology "multilib" is not that accurate (i.e., it's confusing GNU toolchain's multilib) )