This is a followup to my original post on March 9 about issues building
dmd-2.102.2 on an old Linux x86_64 system.

See bugzilla:
https://issues.dlang.org/show_bug.cgi?id=23846

The short answer is it is fixed as of dmd-2.104.0-beta.1, that version
now builds dmd and phobos successfully.