[gitg] Fix crash if the cursor surface is null

[Ignacio Casal Quinteiro <icq src gnome org>]

commit b801f79ee002dae64d3d964456dc04f471f998b6
Author: Ignacio Casal Quinteiro <icq gnome org>
Date:   Sun Dec 20 19:36:24 2015 +0100

    Fix crash if the cursor surface is null

 libgitg/gitg-platform-support.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/libgitg/gitg-platform-support.c b/libgitg/gitg-platform-support.c
index aaad1d8..77c0227 100644
--- a/libgitg/gitg-platform-support.c
+++ b/libgitg/gitg-platform-support.c
@@ -56,6 +56,11 @@ gitg_platform_support_create_cursor_surface (GdkDisplay    *display,
        cursor = gdk_cursor_new_for_display (display, cursor_type);
        surface = gdk_cursor_get_surface (cursor, hot_x, hot_y);
 
+       if (surface == NULL)
+       {
+               return NULL;
+       }
+
        switch (cairo_surface_get_type (surface))
        {
        case CAIRO_SURFACE_TYPE_XLIB: