bug fix: ldd silent about missing dll dependencies

[jannick0]

As of now ldd is silent about missing dll dependencies - and it always returns with 0, regardless if all dll dependencies are found or not.

With the commits kept as minimal as possible, the PR fixes:

• missing dll dependencies are now listed marked with not found (dll dependencies on a dll which is not found are still not listed, of course)
• ldd returns with exit code 1 if not all dll dependencies are found.
• memory leakage as an extra

This bug is a bit painful per se - and, in particular, for the CI function list_dll_deps in ci-library.sh of the MSYS and MINGW repos:

# from ci-library.sh
# List DDL dependencies
list_dll_deps(){
    local target="${1}"
    echo "$(tput setaf 2)MSYS2 DLL dependencies:$(tput sgr0)"
    find "$target" -regex ".*\.\(exe\|dll\)" -print0 | xargs -0 -r ldd | GREP_COLOR="1;35" grep --color=always "msys-.*\|" \
    || echo "        None"
}

1. list_dll_deps could be amended, e.g.,

• for coloring and
• such that CI fails or sends out an email if a dll dependency cannot be resolved (e.g., due to a changed dll file name)

2. The bug persists on Cygwin. In case one of you guys think this should be patched upstream, please go ahead. I am not really involved with the cygwin infrastructure I must admit. Thanks.

I hope this PR sits on the correct branch of the repo. This is my first PR here.

[dscho]

Is this maybe addressing bugs in Cygwin directly?

[jannick0]

Yes - see 2.) above.

[dscho]

In case one of you guys think this should be patched upstream, please go ahead.

I won't have the time (and even if I had the time, I don't like to be treated like a convenience, so I'll decline).