utils: import ptr array lookup with GEqualFunc from GLib 2.54

This fixes the build when using GLib < 2.54.

src/mm-utils.c

@@ -0,0 +1,47 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details:
+ *
+ * Singleton support imported from NetworkManager.
+ *     (C) Copyright 2014 Red Hat, Inc.
+ *
+ * GPtrArray lookup with GEqualFunc imported from GLib 2.48
+ */
+
+#include "mm-utils.h"
+
+#if !GLIB_CHECK_VERSION(2,54,0)
+
+gboolean
+mm_ptr_array_find_with_equal_func (GPtrArray     *haystack,
+				   gconstpointer  needle,
+				   GEqualFunc     equal_func,
+				   guint         *index_)
+{
+  guint i;
+
+  g_return_val_if_fail (haystack != NULL, FALSE);
+
+  if (equal_func == NULL)
+      equal_func = g_direct_equal;
+
+  for (i = 0; i < haystack->len; i++) {
+      if (equal_func (g_ptr_array_index (haystack, i), needle)) {
+          if (index_ != NULL)
+              *index_ = i;
+          return TRUE;
+      }
+  }
+
+  return FALSE;
+}
+
+#endif