More NoGPU compile fixes

I can now build 'most' with skia_gpu=0 on my machine.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2340133003

Review-Url: https://codereview.chromium.org/2340133003
diff --git a/bench/nanobench.cpp b/bench/nanobench.cpp
index ca403f5..5db5137 100644
--- a/bench/nanobench.cpp
+++ b/bench/nanobench.cpp
@@ -483,6 +483,12 @@
     }
 }
 
+// disable warning : switch statement contains default but no 'case' labels
+#if defined _WIN32
+#pragma warning ( push )
+#pragma warning ( disable : 4065 )
+#endif
+
 // If bench is enabled for config, returns a Target* for it, otherwise nullptr.
 static Target* is_enabled(Benchmark* bench, const Config& config) {
     if (!bench->isSuitableFor(config.backend)) {
@@ -517,6 +523,10 @@
     return target;
 }
 
+#if defined _WIN32
+#pragma warning ( pop )
+#endif
+
 static bool valid_brd_bench(sk_sp<SkData> encoded, SkColorType colorType, uint32_t sampleSize,
         uint32_t minOutputSize, int* width, int* height) {
     SkAutoTDelete<SkBitmapRegionDecoder> brd(