Passthrough QEMU_LD_PREFIX to subprocesses with empty environments

[chrisburr]

When running with emulation I've hit a couple of cases where mamba's subprocesses fail due to QEMU_LD_PREFIX not being set causing. I don't particularly like this solution but I don't see a cleaner option other than maybe centralising the creation of subprocesses and having a way of configuring the environment of subprocesses (e.g. MAMBA_ENV_xxxx environment variables).

What do you think?

[wolfv]

I think we should have a list of environment variables that we consider necessary even in a clean environment and propagate all of them. Unfortunately I haven't found such list for Unix / Linux (only for Windows: https://github.com/microsoft/vcpkg-tool/blob/aee79d78ec25ad162197a1f7c6f5a394a9741837/src/vcpkg/base/system.process.cpp#L285 )

[chrisburr]

Yeah, the more I think about it the more I agree.

I have a list that I use for some of my pacakges at work (see below) though I think the list might still need to be configurable as a couple of these are quite domain specific.

    r"DISPLAY",
    r"EDITOR",
    r"HOME",
    r"HOSTNAME",
    r"KRB5.*",
    r"LANG",
    r"LC_.*",
    r"OMP_.*",
    r"QEMU.*",
    r"TERM",
    r"TMPDIR",
    r"TZ",
    r"USER",
    r"VISUAL",
    r"VOMS_.*",
    r"X509_.*",
    r"XRD_.*",