Add dlopen() emulation for systems without it.

For HP-UX 10, emulate using shl_load().
For others, link sudoers plugin statically and use a lookup
table to emulate dlsym().

src/preload.c

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2010 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include "sudo_plugin.h"
+
+extern struct policy_plugin sudoers_policy;
+extern struct io_plugin sudoers_io;
+
+struct sudo_preload_table {
+    const char *name;
+    void *address;
+} sudo_preload_table = {
+    { "sudoers_policy", (void *) &sudoers_policy},
+    { "sudoers_io", (void *) &sudoers_io},
+    { NULL, NULL }
+};