Fix make install target for JVM
Fix make install target for JVM

Basically `nqp_libdir` → `nqp::libdir`.
See 456b08e35eeebaa9255aade221ea8a96f32192aa.

MasterDuke17/rakudo,MasterDuke17/rakudo,labster/rakudo,tony-o/rakudo,nbrown/rakudo,labster/rakudo,softmoth/rakudo,tbrowder/rakudo,rakudo/rakudo,tony-o/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,Gnouc/rakudo,labster/rakudo,Gnouc/rakudo,labster/rakudo,tbrowder/rakudo,tony-o/rakudo,softmoth/rakudo,salortiz/rakudo,tbrowder/rakudo,nbrown/rakudo,salortiz/rakudo,MasterDuke17/rakudo,salortiz/rakudo,softmoth/rakudo,tbrowder/rakudo,rakudo/rakudo,labster/rakudo,rakudo/rakudo,Gnouc/rakudo,tony-o/rakudo,tbrowder/rakudo,salortiz/rakudo,Gnouc/rakudo,Gnouc/rakudo,nbrown/rakudo,salortiz/rakudo,nbrown/rakudo,rakudo/rakudo,tony-o/rakudo,labster/rakudo,tony-o/rakudo,nbrown/rakudo,tbrowder/rakudo,salortiz/rakudo,softmoth/rakudo,rakudo/rakudo,softmoth/rakudo,rakudo/rakudo,nbrown/rakudo,Gnouc/rakudo