Implement $PERL6_HOME fallback in the JVM runner
Implement $PERL6_HOME fallback in the JVM runner

The fallback for the $PERL6_HOME env var was missing in the JVM runner
script.

labster/rakudo,tbrowder/rakudo,labster/rakudo,tbrowder/rakudo,rakudo/rakudo,labster/rakudo,labster/rakudo,salortiz/rakudo,rakudo/rakudo,tony-o/rakudo,rakudo/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,rakudo/rakudo,rakudo/rakudo,tony-o/rakudo,tbrowder/rakudo,tony-o/rakudo,salortiz/rakudo,salortiz/rakudo,salortiz/rakudo,salortiz/rakudo,rakudo/rakudo,tbrowder/rakudo,tony-o/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,labster/rakudo,labster/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tony-o/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,tony-o/rakudo