testbench: make work (better) on solaris
testbench: make work (better) on solaris

do not use non-supported "local" sh keyword

closes https://github.com/rsyslog/liblognorm/issues/147

radu-gheorghe/liblognorm,janmejay/liblognorm,janmejay/liblognorm,radu-gheorghe/liblognorm