[Bugpoint redesign] Output option can now print to STDOUT

Summary:
This also changes all the outs() statements to errs() so the output and
progress streams don't get mixed.

This has been added because D64176 had flaky tests, which I believe were because the reduced file was being catted into `FileCheck`, instead of being pass from STDOUT directly.

Reviewers: chandlerc, dblaikie, xbolva00

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66314

llvm-svn: 369060
diff --git a/llvm/tools/llvm-reduce/TestRunner.cpp b/llvm/tools/llvm-reduce/TestRunner.cpp
index 09548a6..2fd01ab 100644
--- a/llvm/tools/llvm-reduce/TestRunner.cpp
+++ b/llvm/tools/llvm-reduce/TestRunner.cpp
@@ -49,7 +49,7 @@
   if (Result < 0) {
     Error E = make_error<StringError>("Error running interesting-ness test\n",
                                       inconvertibleErrorCode());
-    outs() << toString(std::move(E));
+    errs() << toString(std::move(E));
     exit(1);
   }