rust: fix rustlib dylib IDs in post_install.

This is the less invasive version of Homebrew/brew#2764.

Closes #14490.

Signed-off-by: ilovezfs <[email protected]>

Author: woodruffw

Formula/rust.rb

@@ -1,6 +1,7 @@
 class Rust < Formula
   desc "Safe, concurrent, practical language"
   homepage "https://www.rust-lang.org/"
+  revision 1
 
   stable do
     url "https://static.rust-lang.org/dist/rustc-1.18.0-src.tar.gz"
@@ -101,6 +102,14 @@ def install
     rm_rf prefix/"lib/rustlib/install.log"
   end
 
+  def post_install
+    Dir["#{lib}/rustlib/**/*.dylib"].each do |dylib|
+      chmod 0664, dylib
+      MachO::Tools.change_dylib_id(dylib, "@rpath/#{File.basename(dylib)}")
+      chmod 0444, dylib
+    end
+  end
+
   test do
     system "#{bin}/rustdoc", "-h"
     (testpath/"hello.rs").write <<-EOS.undent