cmake: only build testnative when X11 is available

test/CMakeLists.txt

@@ -116,7 +116,7 @@ if(APPLE)
                               testutils.c)
 elseif(WINDOWS)
     add_executable(testnative testnative.c testnativew32.c testutils.c)
-elseif(SDL_X11)
+elseif(HAVE_X11)
     add_executable(testnative testnative.c testnativex11.c testutils.c)
     target_link_libraries(testnative X11)
 endif()
@@ -313,7 +313,7 @@ else()
         teststreaming
         testviewport
     )
-    if(WINDOWS OR APPLE OR SDL_X11)
+    if(WINDOWS OR APPLE OR HAVE_X11)
         list(APPEND NEEDS_RESOURCES testnative)
     endif()
 endif()