rbinstall.rb: no chdir

* tool/rbinstall.rb (PROLOG_SCRIPT): use the given symlinked
  directory name.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49455 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/rbinstall.rb

@@ -418,7 +418,7 @@ end
 if load_relative
   PROLOG_SCRIPT = <<EOS
 #!/bin/sh\n# -*- ruby -*-
-bindir=`#{CONFIG["CHDIR"]} "${0%/*}" 2>/dev/null; pwd`
+bindir="${0%/*}"
 EOS
   if CONFIG["LIBRUBY_RELATIVE"] != 'yes' and libpathenv = CONFIG["LIBPATHENV"]
     pathsep = File::PATH_SEPARATOR