Fix missing header in OpenGLFunctions.cpp

This patch adds the missing header <tuple> in OpenGLFunctions.cpp to
fix a build error on Windows that the compiler cannot find the
definition of std::tie().

BUG=dawn:190

Change-Id: I35d1f258d3b6197187d626870f3347e195881da8
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9300
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>

src/dawn_native/opengl/OpenGLFunctions.cpp

@@ -15,6 +15,7 @@
 #include "dawn_native/opengl/OpenGLFunctions.h"
 
 #include <cctype>
+#include <tuple>
 
 namespace dawn_native { namespace opengl {