Unit application library.

Library now used in all language modules.
Old 'nxt_app_*' code removed.

See src/test/nxt_unit_app_test.c for usage sample.

src/nxt_unit_sptr.h

@@ -0,0 +1,38 @@
+
+/*
+ * Copyright (C) NGINX, Inc.
+ */
+
+#ifndef _NXT_UNIT_SPTR_H_INCLUDED_
+#define _NXT_UNIT_SPTR_H_INCLUDED_
+
+
+#include <inttypes.h>
+#include <stddef.h>
+#include <string.h>
+
+#include "nxt_unit_typedefs.h"
+
+
+/* Serialized pointer. */
+union nxt_unit_sptr_u {
+    uint8_t   base[1];
+    uint32_t  offset;
+};
+
+
+static inline void
+nxt_unit_sptr_set(nxt_unit_sptr_t *sptr, void *ptr)
+{
+    sptr->offset = (uint8_t *) ptr - sptr->base;
+}
+
+
+static inline void *
+nxt_unit_sptr_get(nxt_unit_sptr_t *sptr)
+{
+    return sptr->base + sptr->offset;
+}
+
+
+#endif /* _NXT_UNIT_SPTR_H_INCLUDED_ */