[gtk+] printing: Fix build with CUPS older than 1.6

[Marek Kašík <mkasik src gnome org>]

commit 059fc5d3d909a4a8590de903cd5e86f6c2d9d481
Author: Marek Kasik <mkasik redhat com>
Date:   Thu Nov 27 17:04:47 2014 +0100

    printing: Fix build with CUPS older than 1.6
    
    Define missing functions ippFirstAttribute(), ippNextAttribute()
    and macro ippGetCollection(). These were added in CUPS 1.6.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=740358

 modules/printbackends/cups/gtkprintbackendcups.c |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)
---
diff --git a/modules/printbackends/cups/gtkprintbackendcups.c 
b/modules/printbackends/cups/gtkprintbackendcups.c
index c90c5ef..15546f7 100644
--- a/modules/printbackends/cups/gtkprintbackendcups.c
+++ b/modules/printbackends/cups/gtkprintbackendcups.c
@@ -297,6 +297,7 @@ pb_module_create (void)
 #define ippGetName(attr) attr->name
 #define ippGetCount(attr) attr->num_values
 #define ippGetGroupTag(attr) attr->group_tag
+#define ippGetCollection(attr, index) attr->values[index].collection
 
 static int
 ippGetRange (ipp_attribute_t *attr,
@@ -306,6 +307,24 @@ ippGetRange (ipp_attribute_t *attr,
   *upper = attr->values[element].range.upper;
   return (attr->values[element].range.lower);
 }
+
+static ipp_attribute_t *
+ippFirstAttribute (ipp_t *ipp)
+{
+  if (!ipp)
+    return (NULL);
+
+  return (ipp->current = ipp->attrs);
+}
+
+static ipp_attribute_t *
+ippNextAttribute (ipp_t *ipp)
+{
+  if (!ipp || !ipp->current)
+    return (NULL);
+
+  return (ipp->current = ipp->current->next);
+}
 #endif
 /*
  * GtkPrintBackendCups