Add libedit as a dependency for rbx.
Add libedit as a dependency for rbx.

* LLVM pulls in libedit, so the linker needs it.
* OS X already ships with libedit.

firstval/ruby-install,FreedomBen/ruby-install,ngpestelos/ruby-install,FreedomBen/ruby-install,boone/ruby-install,bascht/ruby-install,PLOS/ruby-install,boone/ruby-install,regularfry/ruby-install,ngpestelos/ruby-install,regularfry/ruby-install,postmodern/ruby-install,postmodern/ruby-install,PLOS/ruby-install,bascht/ruby-install,firstval/ruby-install