auto merge of rust-lang#10198 : alexcrichton/rust/darwin-quiet, r=jdm

Instead of running dsymutil for all builds, this changes it to only run the program for debug builds.

Closes rust-lang#3495

src/librustc/back/link.rs

@@ -955,8 +955,9 @@ pub fn link_binary(sess: Session,
         sess.abort_if_errors();
     }
 
-    // Clean up on Darwin
-    if sess.targ_cfg.os == abi::OsMacos {
+    // On OSX, debuggers needs this utility to get run to do some munging of the
+    // symbols
+    if sess.targ_cfg.os == abi::OsMacos && sess.opts.debuginfo {
         // FIXME (#9639): This needs to handle non-utf8 paths
         run::process_status("dsymutil", [output.as_str().unwrap().to_owned()]);
     }