$ ./cbuild -a mipsel pkg main/base-cbuild
0:00:00.047 => cbuild: cleaning world...
0:00:00.275 => setting up sysroot for mipsel...
0:00:00.279 => cbuild: installing virtual provider for mipsel...
0:00:00.365 => base-cbuild-0.1-r9: start build (target: pkg), available hardening:
0:00:00.365 =>   +format +pie +ssp +var-init
0:00:00.365 =>   -bti -cet -cfi -cfi-genptr -cfi-icall -int -pac -scp -sst -vis
0:00:00.366 => cbuild: updating software in /opt/cports/bldroot container...
OK: 506 MiB in 59 packages
0:00:01.153 => cbuild: cleaning world...
0:00:01.154 => base-cbuild-0.1-r9: building [meta] for mipsel...
  [host] base-cross-mipsel: unresolved build dependency
0:00:01.213 => base-cbuild-0.1-r9: ERROR: host dependency 'base-cross-mipsel' does not exist