Point to the updated version of some dead links

compiler/rustc_target/src/abi/call/msp430.rs

@@ -1,5 +1,5 @@
 // Reference: MSP430 Embedded Application Binary Interface
-// https://web.archive.org/web/20191221205752/http://www.ti.com/lit/an/slaa534/slaa534.pdf
+// https://www.ti.com/lit/an/slaa534a/slaa534a.pdf
 
 use crate::abi::call::{ArgAbi, FnAbi};
 

src/test/ui/nullable-pointer-iotareduction.rs

@@ -4,7 +4,7 @@
 
 // Iota-reduction is a rule in the Calculus of (Co-)Inductive Constructions,
 // which "says that a destructor applied to an object built from a constructor
-// behaves as expected".  -- https://web.archive.org/web/20100531091244/http://coq.inria.fr/doc/Reference-Manual006.html
+// behaves as expected".  -- https://coq.inria.fr/doc/language/core/conversion.html#iota-reduction
 //
 // It's a little more complicated here, because of pointers and regions and
 // trying to get assert failure messages that at least identify which case