This was already happening for libraries, but not for programs - as a
result, programs built with libraries that contained unicode (eg
cl-unicode, uax-15, ...) would fail to build due to character encoding
issues when loading the FASLs.
Change-Id: I66149b585e85b213d0c026153140a1925536bd29
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1469
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>