Fix some crash-test directives

Author: Zalathar

tests/crashes/125772.rs

@@ -1,5 +1,5 @@
 //@ known-bug: rust-lang/rust#125772
-//@ only-x86_64
+//@ only-64bit
 #![feature(generic_const_exprs)]
 
 struct Outer<const A: i64, const B: i64>();

tests/crashes/131292.rs

@@ -1,5 +1,5 @@
 //@ known-bug: #131292
-//@ only-x86_64
+//@ needs-asm-support
 use std::arch::asm;
 
 unsafe fn f6() {

tests/crashes/34127.rs

@@ -1,6 +1,6 @@
 //@ compile-flags: -g -Copt-level=0 -Z verify-llvm-ir
 //@ known-bug: #34127
-//@ only-x86_64
+//@ only-64bit
 
 pub fn main() {
 let _a = [(); 1 << 63];