busybox

fix bashisms in testsuite/

These places use ${var/search/replace}, $((n++) and
`type -p' constructs which are not-so-standard.
Replace with equivalent constructs.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>