busybox

testsuite: update busybox and bzcat tests

Test scripts that use CONFIG_* variables need to source .config.
Since this wasn't being done for busybox many tests were skipped.
As a result new failures due to changes in help output were missed.

Also remove some unnecessary echos in the bzcat script.

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>