std: Standardize (input, output) param orderings

This functions swaps the order of arguments to a few functions that previously
took (output, input) parameters, but now take (input, output) parameters (in
that order).

The affected functions are:

* ptr::copy
* ptr::copy_nonoverlapping
* slice::bytes::copy_memory
* intrinsics::copy
* intrinsics::copy_nonoverlapping

Closes #22890
[breaking-change]

src/libstd/sys/common/wtf8.rs

@@ -344,8 +344,8 @@ impl Wtf8Buf {
                 Some((surrogate_pos, _)) => {
                     pos = surrogate_pos + 3;
                     slice::bytes::copy_memory(
+                        UTF8_REPLACEMENT_CHARACTER,
                         &mut self.bytes[surrogate_pos .. pos],
-                        UTF8_REPLACEMENT_CHARACTER
                     );
                 },
                 None => return unsafe { String::from_utf8_unchecked(self.bytes) }