[libgnomekbd] libgnomekbd/gkbd-keyboard-drawing.c: fix a segfault

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 1ae17df45b629441f5aa7ed946616b0a17e26dbf
Author: Antonio Ospite <ao2 ao2 it>
Date:   Fri Jan 22 11:46:39 2016 +0100

    libgnomekbd/gkbd-keyboard-drawing.c: fix a segfault
    
    When drawing the keyboard without having set the groups and levels there
    is a segmentation fault:
    
      Program received signal SIGSEGV, Segmentation fault.
      0x00007fffe49ae8c9 in draw_key_label (is_pressed=<optimized out>, xkb_height=<optimized out>, 
xkb_width=<optimized out>, xkb_origin_y=<optimized out>,
          xkb_origin_x=<optimized out>, angle=0, keycode=<optimized out>, drawing=0xa540e0, context=0xca6080) 
at gkbd-keyboard-drawing.c:1017
      1017                    if (drawing->groupLevels[glp] == NULL)
    
    Fix that.
    
    The widget now is able to draw a keyboard without the keys labels, which
    can be useful when testing just the keyboard geometry.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=760988

 libgnomekbd/gkbd-keyboard-drawing.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libgnomekbd/gkbd-keyboard-drawing.c b/libgnomekbd/gkbd-keyboard-drawing.c
index cf32d57..9b8dae3 100644
--- a/libgnomekbd/gkbd-keyboard-drawing.c
+++ b/libgnomekbd/gkbd-keyboard-drawing.c
@@ -1000,7 +1000,7 @@ draw_key_label (GkbdKeyboardDrawingRenderContext * context,
        gint padding;
        gint g, l, glp;
 
-       if (!drawing->xkb || keycode == INVALID_KEYCODE)
+       if (!drawing->xkb || !drawing->groupLevels || keycode == INVALID_KEYCODE)
                return;
 
        padding = 23 * context->scale_numerator / context->scale_denominator;   /* 2.3mm */