How to enable ANSI build for GCL 2.7.1

I'm trying to build GCL 2.7.1 with ANSI CL enabled instead of CLtL1.
There used to be a configure option for that, I think it was
--enable-ansi, but that seems to have gone away, and I can't find any
other configure option that seems relevant.

I was able to build GCL 2.7.1 from a tarball on Linux and the
resulting executable advertises itself as "CLtL1" in the banner.
Looking at lsp/gcl_top.lsp, I see that is due to *FEATURES* lacking
:ansi-cl . Is that an oversight? Is the executable actually ANSI and
mistakenly calling itself CLtL1?

I found an executable ansi_gcl in the unixport directory, but it
likewise claims to be CLtL1 in the banner.

How can I create an ANSI CL GCL?

Thanks for any information, I appreciate it.

Robert