Move headers from server/include to include/maxscale

- Headers now to be included as <maxscale/xyz.h>
- First step, no cleanup of headers has been made. Only moving
  from one place to another + necessary modifications.

include/maxscale/queuemanager.h

@@ -0,0 +1,70 @@
+#ifndef _QUEUEMANAGER_H
+#define _QUEUEMANAGER_H
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+/**
+ * @file queuemanager.h  The Queue Manager header file
+ *
+ *
+ * @verbatim
+ * Revision History
+ *
+ * Date         Who                     Description
+ * 27/04/2016   Martin Brampton         Initial implementation
+ *
+ * @endverbatim
+ */
+
+#include <stdbool.h>
+#include <maxscale/spinlock.h>
+
+#define CONNECTION_QUEUE_LIMIT 1000
+
+typedef struct queue_entry
+{
+    void            *queued_object;
+    long            heartbeat;
+#if defined(SS_DEBUG)
+    long            sequence_check;
+#endif /* SS_DEBUG */
+} QUEUE_ENTRY;
+
+typedef struct queue_config
+{
+    int             queue_limit;
+    int             start;
+    int             end;
+    int             timeout;
+    bool            has_entries;
+    SPINLOCK        queue_lock;
+    QUEUE_ENTRY     *queue_array;
+#if defined(SS_DEBUG)
+    long            sequence_number;
+#endif /* SS_DEBUG */
+} QUEUE_CONFIG;
+
+QUEUE_CONFIG *mxs_queue_alloc(int limit, int timeout);
+void mxs_queue_free(QUEUE_CONFIG *queue_config);
+bool mxs_enqueue(QUEUE_CONFIG *queue_config, void *new_entry);
+bool mxs_dequeue(QUEUE_CONFIG *queue_config, QUEUE_ENTRY *result);
+bool mxs_dequeue_if_expired(QUEUE_CONFIG *queue_config, QUEUE_ENTRY *result);
+
+static inline int
+mxs_queue_count(QUEUE_CONFIG *queue_config)
+{
+    int count = queue_config->end - queue_config->start;
+    return count < 0 ? (count + queue_config->queue_limit + 1): count;
+}
+
+#endif /* QUEUEMANAGER_H */