CI: Fix Mac builds on Travis CI's Xcode 8.3 image

The Travis CI Xcode 8.3 image uses macOS 10.12, where some OS and Xcode
components were changed. This commit finally fixes macOS deployments on
Travis for Xcode 8.3. This commit also reverts a few changes that got
into master while we were trying to fix this.

CI/install/osx/build_app.py

@@ -84,10 +84,9 @@ for i in candidate_paths:
 		for file_ in files:
 			path = root + "/" + file_
 			try:
-				out = check_output("{0}otool -L '{1}'".format(args.prefix, path),
-						stderr=subprocess.STDOUT, shell=True,
+				out = check_output("{0}otool -L '{1}'".format(args.prefix, path), shell=True,
 						universal_newlines=True)
-				if "The file was not recognized as a valid object file" in out:
+				if "is not an object file" in out:
 					continue
 			except:
 				continue