Fixed: It cannot execute the "jake" command correctly in the Cappuccino repository directory when it's not the Apple OS.

When running the "jake" command in the repository directory, it will print:
$ jake --help
narwhal/packages/narwhal-jsc/bin/narwhal-jsc: line 33: narwhal/packages/narwhal-jsc/bin/narwhal-jscore: No such file or directory

Fixes #2181