[master] comment cleanup: s/RBTree/ZoneTree/

committing at my discretion.

src/lib/datasrc/memory/memory_client.cc

@@ -125,7 +125,7 @@ public:
     //
     // In order for wildcard matching to work correctly in the zone finder,
     // we must ensure that a node for the wildcarding level exists in the
-    // backend RBTree.
+    // backend ZoneTree.
     // E.g. if the wildcard name is "*.sub.example." then we must ensure
     // that "sub.example." exists and is marked as a wildcard level.
     // Note: the "wildcarding level" is for the parent name of the wildcard

src/lib/datasrc/memory/zone_finder.cc

@@ -137,7 +137,7 @@ struct FindState {
 };
 
 // A callback called from possible zone cut nodes and nodes with DNAME.
-// This will be passed from findNode() to \c RBTree::find().
+// This will be passed from findNode() to \c ZoneTree::find().
 bool cutCallback(const ZoneNode& node, FindState* state) {
     // We need to look for DNAME first, there's allowed case where
     // DNAME and NS coexist in the apex. DNAME is the one to notice,
@@ -264,7 +264,7 @@ createFindResult(const RRClass& rrclass,
 // it should always succeed.
 //
 // node_path must store valid search context (in practice, it's expected
-// to be set by findNode()); otherwise the underlying RBTree implementation
+// to be set by findNode()); otherwise the underlying ZoneTree implementation
 // throws.
 //
 // If the zone is not considered NSEC-signed or DNSSEC records were not

src/lib/datasrc/tests/memory/zone_finder_unittest.cc

@@ -897,7 +897,7 @@ InMemoryZoneFinderTest::emptyNodeCheck(
     ZoneFinder::FindResultFlags expected_flags)
 {
     /*
-     * The backend RBTree for this test should look like as follows:
+     * The backend ZoneTree for this test should look like as follows:
      *          example.org
      *               |
      *              baz (empty; easy case)