layers: Include all 4 Linux WSI interfaces

Change-Id: I20b0d64c90e6da940f45b31abf0330b2a415655d
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 35610fe..46940fb 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,7 +21,7 @@
     #   TODO: Basic support is present for Xlib but is untested.
     #         Mir support is stubbed in but unimplemented and untested.
     option(BUILD_WSI_XCB_SUPPORT "Build XCB WSI support" ON)
-    option(BUILD_WSI_XLIB_SUPPORT "Build Xlib WSI support" OFF)
+    option(BUILD_WSI_XLIB_SUPPORT "Build Xlib WSI support" ON)
     option(BUILD_WSI_WAYLAND_SUPPORT "Build Wayland WSI support" OFF)
     option(BUILD_WSI_MIR_SUPPORT "Build Mir WSI support" OFF)