Allow tests to run on native EGL.

Adds support for Linux and Android native EGL testing.
This can be useful for doing performance comparisons of ANGLE vs
a native GL driver. Only enabled for the trace perf tests due to
limitations in the test harness.

Bug: angleproject:4596
Change-Id: Iba6d3ccd7c1275cf095893fab824a0ea33dc3a79
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2116254
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>

util/windows/WGLWindow.cpp

@@ -71,9 +71,15 @@ WGLWindow::~WGLWindow() {}
 // Internally initializes GL resources.
 bool WGLWindow::initializeGL(OSWindow *osWindow,
                              angle::Library *glWindowingLibrary,
+                             angle::GLESDriverType driverType,
                              const EGLPlatformParameters &platformParams,
                              const ConfigParameters &configParams)
 {
+    if (driverType != angle::GLESDriverType::SystemWGL)
+    {
+        return false;
+    }
+
     glWindowingLibrary->getAs("wglGetProcAddress", &gCurrentWGLGetProcAddress);
 
     if (!gCurrentWGLGetProcAddress)