[mutter] Fix crash when starting not on first workspace

[Owen Taylor <otaylor src gnome org>]

commit 4be8e155d14b0900c87892d451d676d70e3bd864
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Mon Jul 6 08:41:59 2009 +0100

    Fix crash when starting not on first workspace
    
    If we are starting on something other than the first workspace,
    meta_compositor_switch_workspace() will be called before
    meta_compositor_manage_screen(); guard against that.

 src/compositor/compositor.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index a6130e7..9bcdb38 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -691,6 +691,9 @@ meta_compositor_switch_workspace (MetaCompositor     *compositor,
 
   DEBUG_TRACE ("meta_compositor_switch_workspace\n");
 
+  if (!info) /* During startup before manage_screen() */
+    return;
+
   info->switch_workspace_in_progress++;
 
   if (!info->plugin_mgr ||