Ignoring working crahes test in GCC backend

tests/crashes/118244.rs

@@ -1,5 +1,6 @@
 //@ known-bug: #118244
 //@ compile-flags: -Cdebuginfo=2
+//@ ignore-backends: gcc
 
 #![allow(incomplete_features)]
 #![feature(generic_const_exprs)]

tests/crashes/134479.rs

@@ -1,5 +1,6 @@
 //@ known-bug: #134479
 //@ compile-flags: -Csymbol-mangling-version=v0 -Cdebuginfo=1
+//@ ignore-backends: gcc
 
 #![feature(generic_const_exprs)]
 

tests/crashes/139462.rs

@@ -1,5 +1,6 @@
 //@ known-bug: #139462
 //@ compile-flags: -Cdebuginfo=2
+//@ ignore-backends: gcc
 #![feature(unsafe_binders)]
 use std::unsafe_binder::wrap_binder;
 fn main() {

tests/crashes/34127.rs

@@ -1,6 +1,7 @@
 //@ compile-flags: -g -Copt-level=0 -Z verify-llvm-ir
 //@ known-bug: #34127
 //@ only-64bit
+//@ ignore-backends: gcc
 
 pub fn main() {
 let _a = [(); 1 << 63];