git: openjdk/leyden: premain: support benchmarking for new workflow

[duke]

Changeset: f11f4604
Author:    Andrew Dinn <adinn at redhat.com>
Date:      2024-05-14 12:47:29 +0000
URL:       https://git.openjdk.org/leyden/commit/f11f4604c48d65ea05a30dd37b2ca3419643532c

support benchmarking for new workflow

tidy up and document extra caller options

! test/hotspot/jtreg/premain/javac_new_workflow/Makefile
+ test/hotspot/jtreg/premain/javac_new_workflow/run_bench.sh
+ test/hotspot/jtreg/premain/lib/bench-lib-new-workflow.sh