tests/ui/lint/large_assignments: only-x86_64 -> only-64bit

So that devs on aarch64 can also bless tests.

Author: Enselic

tests/ui/lint/large_assignments/copy_into_box_rc_arc.rs

@@ -2,7 +2,7 @@
 #![feature(large_assignments)]
 #![move_size_limit = "1000"]
 // build-fail
-// only-x86_64
+// only-64bit
 
 // edition:2018
 // compile-flags: -Zmir-opt-level=1

tests/ui/lint/large_assignments/large_future.rs

@@ -2,7 +2,7 @@
 #![cfg_attr(attribute, feature(large_assignments))]
 #![cfg_attr(attribute, move_size_limit = "1000")]
 // build-fail
-// only-x86_64
+// only-64bit
 // revisions: attribute option
 // [option]compile-flags: -Zmove-size-limit=1000
 

tests/ui/lint/large_assignments/move_into_box_rc_arc.rs

@@ -2,7 +2,7 @@
 #![feature(large_assignments)]
 #![move_size_limit = "1000"]
 // build-fail
-// only-x86_64
+// only-64bit
 
 // edition:2018
 // compile-flags: -Zmir-opt-level=0