unsigned -> int for counts and indices in picture-related code

bench/RTreeBench.cpp

Index: bench/RTreeBench.cpp
diff --git a/bench/RTreeBench.cpp b/bench/RTreeBench.cpp
index 6f76bd19bdf639e2192089b66a2a7d90cb4e1586..3b3dc72a3ed5d7c1eb60986292d4e718f4f71217 100644
--- a/bench/RTreeBench.cpp
+++ b/bench/RTreeBench.cpp
@@ -79,7 +79,7 @@ protected:
     void onDraw(const int loops, SkCanvas* canvas) override {
         SkRandom rand;
         for (int i = 0; i < loops; ++i) {
-            SkTDArray<unsigned> hits;
+            SkTDArray<int> hits;
             SkRect query;
             query.fLeft   = rand.nextRangeF(0, GENERATE_EXTENTS);
             query.fTop    = rand.nextRangeF(0, GENERATE_EXTENTS);