Memoize in TeX Live

[Karl Berry]

    https://github.com/sasozivanovic/memoize/issues/11

Siep, Akira, all - to summarize the issue, an external Perl is not used
for programs listed in shell_escape_programs, per runscript.tlu:649 (not
is_restricted_progname).

So ... when TEXLIVE_WINDOWS_TRY_EXTERNAL_PERL=1, why not try the
external Perl for executing shell_escape_programs? After all, if a user
can create a problematic perl in PATH, they can already do anything they
want to circumvent TL's safety measures. Am I missing something obvious?

Otherwise, the problem is that memoize-extract.pl cannot be executed on
Windows, since our builtin tlperl does not have the needed dependencies,
most notably PDF::API2, and I doubt we want to add that.

The only other Perl program currently in shell_escape_programs is
repstopdf, which has no non-core dependencies, so it's not an issue.
But the same question could certainly come up in the future.

Wdyt? --thanks, karl.