mise.run downloads the wrong musl/glibc build

[splinter98]

Describe the bug
When downloading mise using https://mise.run | sh it downloads and uses the incorrect libc build.

on OS with glibc it downloads musl builds and on musl OSes it downloads glibc builds.

Whilst musl builds will work on glibc OSes it will then also install musl pre-builds of python which will surprise users when installing packages from pypi.

To Reproduce
On any linux machine that uses glibc

$ curl https://mise.run | sh
$ ldd ~/.local/bin/mise
    statically linked

On Alpine (a MUSL build)

$ curl https://mise.run | sh
$ ldd ~/.local/bin/mise
Error loading shared library libgcc_s.so.1: No such file or directory (needed by /root/.local/bin/mise)
        librt.so.1 => /lib64/ld-linux-x86-64.so.2 (0x7f48b721e000)
        libpthread.so.0 => /lib64/ld-linux-x86-64.so.2 (0x7f48b721e000)
        libm.so.6 => /lib64/ld-linux-x86-64.so.2 (0x7f48b721e000)
        libdl.so.2 => /lib64/ld-linux-x86-64.so.2 (0x7f48b721e000)
        libc.so.6 => /lib64/ld-linux-x86-64.so.2 (0x7f48b721e000)

Expected behavior
On Glibc linux

$ ldd ~/.local/bin/mise
        linux-vdso.so.1 (0x00007ffd27f0c000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f26cafd6000)
        librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f26cafd1000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f26cafcc000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f26caee5000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f26caee0000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f26cacb7000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f26cc29a000)

on Alpine:

$ curl https://mise.run | sh
$ ldd ~/.local/bin/mise
    statically linked

mise doctor output

Not Applicable

Additional context
A quick read of packaging/standalone/install.envsubst#L45 suggests that the logic is inverted:

if type ldd >/dev/null 2>/dev/null; then
	libc=$(ldd /bin/ls | grep 'musl' | head -1 | cut -d ' ' -f1)
	if [ -z "$libc" ]; then
		musl="-musl"
	fi
fi

We're checking to see if musl is in /bin/ls however the -z is testing if empty and then appends the -musl. But this logic should be the otherway around.

Whilst the fix is simple, we also may want to warn users if they've got the incorrect of python installed (or any other tool that has similar logic).

[autarch]

I just now noticed that this was changed. It really would be nice to have a way to at least force the install script to use the musl release, for the case where you want to run mise on a machine with an older glibc than the one mise was compiled with. I have to do some stuff with RHEL 7 at work, for example.

[jdx]

we should have a way to override things in mise.run