kselftests.inc: add libc6-utils runtime dependency
kselftests.inc: add libc6-utils runtime dependency

sysctl test requires getconf.

tools/testing/selftests/sysctl/sysctl.sh:108:
    if ! which getconf 2> /dev/null > /dev/null; then
        echo "$0: You need getconf installed"

Reported-by: Sumit Semwal <d6930da0d649c01d063dcca4d796c2ac2cbb68ba@linaro.org>
Signed-off-by: Fathi Boudra <7cd6e55cc07a66bc71d7901a4cddfe6c22aab659@linaro.org>

fboudra/meta-96boards,96boards/meta-96boards,kraj/meta-96boards,mrchapp/meta-96boards,kraj/meta-96boards