Skip MultithreadingTest.MultiCreateContext on Ozone

On Linux this test is supported with GLX but not EGL, so Ozone (which
uses EGL) fails. Update the test suppression to avoid Linux Ozone.

TBR=geofflang@chromium.org
Bug: angleproject:4725
Change-Id: I9e85b51a01ab5b25c6cbbdbcdbbfb4b21b7a6152
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2270021
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>

src/tests/gl_tests/MultithreadingTest.cpp

@@ -205,7 +205,7 @@ TEST_P(MultithreadingTest, MultiContextDraw)
 TEST_P(MultithreadingTest, MultiCreateContext)
 {
     // Supported by CGL, GLX, and WGL (https://anglebug.com/4725)
-    ANGLE_SKIP_TEST_IF(!IsWindows() && !IsLinux() && !IsOSX());
+    ANGLE_SKIP_TEST_IF(!(IsWindows() || (IsLinux() && !IsOzone()) || IsOSX()));
 
     EGLWindow *window  = getEGLWindow();
     EGLDisplay dpy     = window->getDisplay();