Fix a couple of harmless compiler warnings

In each widget's *_geometry function, two warnings were generated, e.g.:
 warning: ‘geometry.y’ is used uninitialized in this function
 warning: ‘geometry.x’ is used uninitialized in this function

Found by gogonkt with GCC 4.2.4 on gentoo.

Signed-off-by: Uli Schlachter <psychon@znc.in>

widgets/graph.c

@@ -153,6 +153,7 @@ graph_geometry(widget_t *widget, screen_t *screen, int height, int width)
     area_t geometry;
     graph_data_t *d = widget->data;
 
+    geometry.x = geometry.y = 0;
     geometry.height = height;
     geometry.width = d->width;
 

widgets/imagebox.c

@@ -69,6 +69,8 @@ imagebox_geometry(widget_t *widget, screen_t *screen, int height, int width)
         geometry.height = 0;
     }
 
+    geometry.x = geometry.y = 0;
+
     return geometry;
 }
 

widgets/progressbar.c

@@ -158,6 +158,8 @@ progressbar_geometry(widget_t *widget, screen_t *screen, int height, int width)
         geometry.width = pb_width + 2 * (d->border_width + d->border_padding);
     }
 
+    geometry.x = geometry.y = 0;
+
     return geometry;
 }
 

widgets/systray.c

@@ -45,6 +45,8 @@ systray_geometry(widget_t *widget, screen_t *screen, int height, int width)
     /** \todo use class hints */
     geometry.width = MIN(n * height, width);
 
+    geometry.x = geometry.y = 0;
+
     return geometry;
 }
 

widgets/textbox.c

@@ -72,6 +72,8 @@ textbox_geometry(widget_t *widget, screen_t *screen, int height, int width)
     else
         geometry.width = MIN(d->extents.width + d->margin.left + d->margin.right, width);
 
+    geometry.x = geometry.y = 0;
+
     return geometry;
 }