Remove args cleanup code.

As of 91c3eee173, the global ARGC and ARGV
no longer reference dynamically-allocated memory, so they don't need to
be cleaned up.

library/std/src/sys/unix/mod.rs

@@ -123,7 +123,6 @@ pub unsafe fn init(argc: isize, argv: *const *const u8) {
 // SAFETY: must be called only once during runtime cleanup.
 // NOTE: this is not guaranteed to run, for example when the program aborts.
 pub unsafe fn cleanup() {
-    args::cleanup();
     stack_overflow::cleanup();
 }