Add wrapper functions for dlopen() et al so that we can support

statically compiling in the sudoers plugin but still allow other
plugins to be loaded.  The new --enable-static-sudoers configure
option will cause the sudoers plugin to be compiled statically into
the sudo binary.  This does not prevent other plugins from being
loaded as per sudo.conf.

src/sudo.h

@@ -266,4 +266,7 @@ void save_signals(void);
 /* gidlist.c */
 int parse_gid_list(const char *gidstr, const gid_t *basegid, GETGROUPS_T **gidsp);
 
+/* preload.c */
+void preload_static_symbols(void);
+
 #endif /* _SUDO_SUDO_H */