cleanup: apply const to read-only iterators

Apply const to read-only iterators.

Change-Id: Ib58f98596cb9f185d3b16a0b1fbd895dd37d3fd6
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/manager.cpp b/manager.cpp
index a64300c..0a30625 100644
--- a/manager.cpp
+++ b/manager.cpp
@@ -83,7 +83,7 @@
     ids.clear();
 
     /* Grab the list of blobs and extend the local list */
-    for (auto& h : handlers)
+    for (const auto& h : handlers)
     {
         std::vector<std::string> blobs = h->getBlobIds();
         ids.insert(ids.end(), blobs.begin(), blobs.end());
@@ -144,7 +144,7 @@
     /* Find a handler. */
     GenericBlobInterface* handler = nullptr;
 
-    for (auto& h : handlers)
+    for (const auto& h : handlers)
     {
         if (h->canHandleBlob(path))
         {