xwayland: Fix build without GBM

The present code in Xwayland cannot be used without GBM, so if GBM is
not available (or too old), the build would fail.

Make sure we do not use the present code without GBM support.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>

hw/xwayland/meson.build

@@ -97,7 +97,10 @@ if build_glamor
         srcs += 'xwayland-glx.c'
     endif
     if gbm_dep.found()
-        srcs += 'xwayland-glamor-gbm.c'
+        srcs += [
+                  'xwayland-glamor-gbm.c',
+                  'xwayland-present.c'
+                ]
     endif
     if build_eglstream
         eglstream_protodir = eglstream_dep.get_pkgconfig_variable('pkgdatadir')
@@ -111,7 +114,6 @@ if build_glamor
 
         srcs += 'xwayland-glamor-eglstream.c'
     endif
-    srcs += 'xwayland-present.c'
     if build_xv
         srcs += 'xwayland-glamor-xv.c'
     endif

hw/xwayland/xwayland-screen.c

@@ -943,10 +943,11 @@ xwl_screen_init(ScreenPtr pScreen, int argc, char **argv)
            xwl_screen->glamor = 0;
         }
     }
-
+#ifdef GLAMOR_HAS_GBM
     if (xwl_screen->glamor && xwl_screen->rootless)
         xwl_screen->present = xwl_present_init(pScreen);
-#endif
+#endif /* GLAMOR_HAS_GBM */
+#endif /* XWL_HAS_GLAMOR */
 
     if (!xwl_screen->glamor) {
         xwl_screen->CreateScreenResources = pScreen->CreateScreenResources;