libtinfo5 is required for hermetic LLVM toolchain

[phlax]

There is a bug in LLVM where a shared lib leaked into their static build

This affects any installation of static LLVM 18 (and i think some other versions also)

This can be resolved relatively easily in some cases - eg on Debian/Ubuntu systems (up to 12/22.x respectively) with:

apt-get install libtinfo5

however on newer versions this package is no longer available (in favour of libtinfo6)

for our debian-based build env we fetch the package from the earlier distro version https://github.com/envoyproxy/envoy-build-tools/blob/e2420cc813171c6aad9aa0d62b0544b68bc6504d/docker/linux/debian/fun.sh#L125-L128

    # Workaround https://github.com/llvm/llvm-project/issues/75490
    curl -LO "http://deb.debian.org/debian/pool/main/n/ncurses/libtinfo5_6.4-4_${DEB_ARCH}.deb"
    dpkg -i "libtinfo5_6.4-4_${DEB_ARCH}.deb"
    rm "libtinfo5_6.4-4_${DEB_ARCH}.deb"

upstream issue is llvm/llvm-project#75490

i think we can probably resolve this by updating LLVM to 19+