Merge branch 'posix-dent-export' into 'master'

eliminate function export struct workaround for posix_dent

See merge request redox-os/relibc!1287

src/header/dirent/cbindgen.toml

@@ -18,3 +18,6 @@ cpp_compat = true
 
 [enum]
 prefix_with_name = true
+
+[export]
+include = ["posix_dent"]

src/header/dirent/mod.rs

@@ -394,6 +394,3 @@ pub extern "C" fn seekdir(dir: &mut DIR, off: c_long) {
 pub extern "C" fn telldir(dir: &mut DIR) -> c_long {
     dir.opaque_offset as c_long
 }
-
-#[unsafe(no_mangle)]
-pub unsafe extern "C" fn cbindgen_stupid_struct_user_for_posix_dent(_: posix_dent) {}