[klibc] remove some 'make -s' build spew

Use $(kecho) to remove 'GEN klcc/klibc.config' log message from
'make --silent' output.

Signed-off-by: Greg Thelen <gthelen@google.com>
Link: https://www.zytor.com/pipermail/klibc/2018-February/003979.html
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
1 file changed