The tools built with buildGraalVmNativeImage have broken UTF-8 support
when not properly setting the locale, e.g.
$ bb -e '(prn "bépo àê")'
"b??po ????"
This commit sets the locale to en_US.UTF-8 by default, which fixes that.
For now it only takes care of the single Jar <-> single Executable case.
This will take care of the majority (all?) use cases we have in nixpkgs
currently.