Update the nqpjs to the new code organisation.
Use HLLBackend::JavaScript from nqp-js.nqp.
Emit modules instead of .js files so that ender doesn't cause problems.
fixjsstyle --strict --nojsdoc nqp-runtime-core/bootstrap.js nqp-runtime-core/code_ref.js nqp-runtime-core/ctx.js nqp-runtime-core/hash.js nqp-runtime-core/helpers.js nqp-runtime-core/null.js nqp-runtime-core/reprs.js nqp-runtime-core/runtime.js nqp-runtime-core/serialization_context.js nqp-runtime-core/serialization.js nqp-runtime-core/serialization_writer.js nqp-runtime-core/sixmodel.js
Fix some errors reported by make lint (gjslint).
Fix some errors reported by make lint (gjslint).