Explicitly run perl for OpenSSL Configure

[smaeul]

OpenSSL's Configure script is missing a shebang. On some platforms,
execve falls back to execution with the shell. Some other platforms,
like musl, will fail with an exec format error. Avoid this by calling
perl explicitly (since it's a perl script).

[rust-highfive]

r? @aturon

(rust_highfive has picked a reviewer for you, use r? to override)

[Mark-Simulacrum]

We'd want to also update the sanity checks and add perl to the configuration if we're going to do this. Sanity checks are here: https://github.com/rust-lang/rust/blob/master/src/bootstrap/sanity.rs#L124 and configuration will need to be updated both in the loader (look at how nodejs is done) and config.toml.example in the root will also need to be updated.

r? @Mark-Simulacrum

[smaeul]

I'm not sure why any of that is necessary (although it might be nice to have). The status quo is that perl is not configurable, and nobody has complained about that. This does not change which perl is called. This is just replicating what the existing code does already at the beginning of the Configure script:

:
eval 'exec perl -S $0 ${1+"$@"}'
    if $running_under_some_shell;

The only reason this change is necessary at all is because the script is designed for decades-old UNIX systems without #! (from man perlrun, under -S):

To start up sh rather than csh, some systems may have to replace the "#!" line with a line containing just a colon, which will be politely ignored by Perl.

-S is removed because it was already a no-op, as we ran script by its full path.

If you want, I can replace Command::new("perl"); with Command::new("sh");, since the file is just as much a "shell script" as "Perl script", but I thought it would be better to avoid the gratuitous indirection.

[Mark-Simulacrum]

Sure, if you don't want to implement that I'm happy to r+ now. Could you file an issue for the steps I propose though? It'd be a nice to have, at least.

[aidanhs]

@bors r=Mark-Simulacrum rollup

[bors]

📌 Commit adfebed has been approved by Mark-Simulacrum