fix last warnings on w64 and turn on w.a.e.

bench/nanobench.cpp

Index: bench/nanobench.cpp
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index e0d6da84eab8956eb2e5f9d5bb973da0307006a9..36a9177e576e38e2a47ba702e42644b86f6f6213 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -525,7 +525,7 @@ public:
             SkString name = SkOSPath::Basename(path.c_str());
             fSourceType = "skp";
             fBenchType  = "recording";
-            fSKPBytes = SkPictureUtils::ApproximateBytesUsed(pic);
+            fSKPBytes = static_cast<double>(SkPictureUtils::ApproximateBytesUsed(pic));
             fSKPOps   = pic->approximateOpCount();
             return SkNEW_ARGS(RecordingBench, (name.c_str(), pic.get(), FLAGS_bbh));
         }