There are several thing to note:

• You are building as root. That is usually not recommended
• I've been digging the git repo history and I cannot find any tr command that takes a-zA-Z as (part of) its arguments
• As Configure spawns quite a number of subshells, can it be that you have some .bashrc for whatever shell you use that does stuff that are not appropriate for the build flow?
• Is your $PATH sane? Do you have some weird tr command somehwere in your $PATH
• You stripped (some more variables assigned, some tools used from /opt/freeware/bin). Is tr one of them? (what commands do you actually need from /opt/freeware/bin?)