Suppress MSVC C4756 (constant arithmetic overflow) in fiddle examples

Bug: skia:
Change-Id: I5611ac4b91baf67c0d895167b3da4ef69a8972bb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/201690
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Auto-Submit: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index baa34f4..07df33b 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -2265,10 +2265,13 @@
     test_app("fiddle_examples") {
       sources = [
         "tools/fiddle/examples.cpp",
-        "tools/fiddle/examples.h"
+        "tools/fiddle/examples.h",
       ]
       sources += examples_sources
       include_dirs = [ "tools" ]
+      if (is_win) {
+        cflags = [ "/wd4756" ]  # Overflow in constant arithmetic
+      }
       deps = [
         ":skia",
         ":skia.h",