eliminate function export workaround for flock struct

src/header/fcntl/cbindgen.toml

@@ -7,3 +7,6 @@ cpp_compat = true
 
 [enum]
 prefix_with_name = true
+
+[export]
+include = ["flock"]

src/header/fcntl/mod.rs

@@ -112,9 +112,6 @@ pub unsafe extern "C" fn openat(
     Sys::openat(fd, path, oflag, mode).or_minus_one_errno()
 }
 
-#[unsafe(no_mangle)]
-pub unsafe extern "C" fn cbindgen_stupid_struct_user_for_fcntl(_: flock) {}
-
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn posix_fallocate(fd: c_int, offset: off_t, length: off_t) -> c_int {
     // Length can't be zero and offset must be positive.