PR 30991: srcfiles tarball feature

PR 30991: srcfiles tarball feature

* srcfiles.cxx: Introduce new --zip option that places all the
    source files associated with a specified dwarf/elf file
    into a zip file and sends it to stdout. Files may be
    fetched from debuginfod (if applicable) or locally as
    a backup.
    Added -b option to disable the backup of checking
    for files locally in -z mode.

* run-srcfiles-self.sh: Added test-case for the new zip
    feature that archives the source files of the srcfiles
    tool and checks archive integrity. An additional test
    ensures that if debuginfod is enabled, the files are
    fetched and archived properly while maintaing integrity.

* debuginfod-subr.sh: On very slow/remote storage, it can
    take O(minute) to finish indexing the entire elfutils
    build tree, so a wait_ready4 shell function is one
    way to let a longer debuginfod wait operation work.

* srcfiles.1, NEWS: Added documentation for the new zip feature.

* configure.ac: Simplify check for libarchive for srcfiles.cxx
    by integrating it into the same check for debuginfod.

* Makefile.am: build with local copy of debuginfod-client.

Example:
% ./src/srcfiles -z -e /bin/ls > output.zip

https://sourceware.org/bugzilla/show_bug.cgi?id=30991

Signed-off-by: Housam Alamour <halamour@redhat.com>