Fix 'range-loop-analysis' warnings

As reported by Apple clang 12, fix a couple of instances where we make
unnecessary copies in range-based for loops:

    loop variable 'entry' is always a copy because the range of type
    'const flatbuffers::Vector<flatbuffers::Offset<Collection> >' does
    not return a reference [-Wrange-loop-analysis]

        for (const auto& entry : *open->entries()) {
                         ^

    note: use non-reference type 'const Collections::KVStore::Collection *'
        for (const auto& entry : *open->entries()) {
             ^~~~~~~~~~~~~~~~~~~

Change-Id: I0967c0e74193588c6354d0e06709942a1068e9cf
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/137829
Tested-by: Build Bot <[email protected]>
Reviewed-by: Richard de Mellow <[email protected]>

Author: daverigby

engines/ep/src/collections/flush.cc

@@ -404,7 +404,7 @@ flatbuffers::DetachedBuffer Flush::encodeOpenCollections(
                 currentCollections, "encodeOpenCollections()");
         auto open = flatbuffers::GetRoot<Collections::KVStore::OpenCollections>(
                 currentCollections.data());
-        for (const auto& entry : *open->entries()) {
+        for (const auto* entry : *open->entries()) {
             // For each currently open collection, is it in the dropped map?
             auto result = droppedCollections.find(entry->collectionId());
 
@@ -529,7 +529,7 @@ flatbuffers::DetachedBuffer Flush::encodeOpenScopes(
         auto fbData = flatbuffers::GetRoot<Collections::KVStore::Scopes>(
                 existingScopes.data());
 
-        for (const auto& entry : *fbData->entries()) {
+        for (const auto* entry : *fbData->entries()) {
             auto result = droppedScopes.find(entry->scopeId());
 
             // If not found in dropped scopes add to output
@@ -561,4 +561,4 @@ flatbuffers::DetachedBuffer Flush::encodeOpenScopes(
     return builder.Release();
 }
 
-} // namespace Collections::VB
+} // namespace Collections::VB