internal/rosa: parallel perl tests

This is found in the github action, the test target does not appear to support parallelisation.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/perl.go

@@ -22,7 +22,10 @@ echo 'print STDOUT "1..0 # Skip broken test\n";' > ext/Pod-Html/t/htmldir3.t
 	-Dldflags="${LDFLAGS}" \
 	-Doptimize='-O2 -fno-strict-aliasing' \
 	-Duseithreads
-make "-j$(nproc)" test
+make \
+	"-j$(nproc)" \
+	TEST_JOBS=256 \
+	test_harness
 make DESTDIR=/work install
 `, pkg.Path(AbsUsrSrc.Append("perl"), true, pkg.NewHTTPGetTar(
 		nil,