Add ColorCodecSrc for testing/comparison on color corrected decodes

bench/nanobench.cpp

Index: bench/nanobench.cpp
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index 5e26b483951db10fc45ef47623907faeb34b1ccc..7999ad5c61915bbeaa42b5983ff406dd923de51f 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -606,7 +606,7 @@ public:
         fUseMPDs.push_back() = false;
 
         // Prepare the images for decoding
-        if (!CollectImages(&fImages)) {
+        if (!CollectImages(FLAGS_images, &fImages)) {
             exit(1);
         }