configure: print feature settings overview

configure: print feature settings overview

elfutils can be configured in various ways. But we expect certain
settings for the features that we explicitly support. Print an
overview of all settings, plus their recommended setting, at the
end of the configure run.

=====================================================================
        elfutils: 0.161 (eu_version: 161)
=====================================================================

    Prefix                             : /opt/local/install/elfutils
    Program prefix ("eu-" recommended) : eu-
    Source code location               : /home/mark/src/elfutils
    Maintainer mode                    : yes
    libebl modules subdirectory        : elfutils
    build arch                         : x86_64-unknown-linux-gnu

  RECOMMENDED FEATURES (should all be yes)
    gzip support                       : yes
    bzip2 support                      : yes
    lzma/xz support                    : yes
    libstdc++ demangle support         : yes
    File textrel check                 : yes
    Symbol versioning                  : yes

  NOT RECOMMENDED FEATURES (should all be no)
    Experimental thread safety         : no

  OTHER FEATURES
    Deterministic archives by default  : false
    Native language support            : yes

  EXTRA TEST FEATURES (used with make check)
    debug branch prediction            : no
    gprof support                      : no
    gcov support                       : no
    run all tests under valgrind       : no
    use rpath in tests                 : no
    test biarch                        : yes

Signed-off-by: Mark Wielaard <mjw@redhat.com>