Avoid defining snprintf when MSVC provides it

src/core/SkString.cpp

Index: src/core/SkString.cpp
diff --git a/src/core/SkString.cpp b/src/core/SkString.cpp
index b43351599f114c0d7f0b3a1d2e179e3a26b3bca1..216cfeb0bd090cd00bf1cc9a3a968f8fb308b05f 100644
--- a/src/core/SkString.cpp
+++ b/src/core/SkString.cpp
@@ -17,7 +17,7 @@
 // number of bytes (on the stack) to receive the printf result
 static const size_t kBufferSize = 1024;
 
-#ifdef SK_BUILD_FOR_WIN
+#if defined(_MSC_VER) && _MSC_VER < 1900
     #define VSNPRINTF(buffer, size, format, args) \
         _vsnprintf_s(buffer, size, _TRUNCATE, format, args)
     #define SNPRINTF    _snprintf