fixup! Add dl_iterate_phdr for openbsd

Author: tesuji

src/unix/bsd/netbsdlike/openbsd/mod.rs

@@ -1546,7 +1546,7 @@ extern "C" {
     ) -> *mut ::c_void;
     // #include <link.h>
     pub fn dl_iterate_phdr(
-        callback: Option<
+        callback: ::Option<
             unsafe extern "C" fn(
                 info: *mut dl_phdr_info,
                 size: usize,