update_engine: Use C++11 range-based for loop when possible.

This cleanup just simplifies the notation of several for loops using
the new range-based syntax.

BUG=None
TEST=`FEATURES=test USE="lang clang" emerge-link update_engine`

Change-Id: I2120a1b1c3fd00e9a02a62abfa8427932080d0f9
Reviewed-on: https://chromium-review.googlesource.com/227897
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
diff --git a/test_utils.cc b/test_utils.cc
index 251ed78..4a49fb2 100644
--- a/test_utils.cc
+++ b/test_utils.cc
@@ -190,9 +190,8 @@
   EXPECT_FALSE(iter.IsErr());
   EXPECT_TRUE(expected_paths.empty());
   if (!expected_paths.empty()) {
-    for (set<string>::const_iterator it = expected_paths.begin();
-         it != expected_paths.end(); ++it) {
-      LOG(INFO) << "extra path: " << *it;
+    for (const string& path : expected_paths) {
+      LOG(INFO) << "extra path: " << path;
     }
   }
 }