Fix windows build after crossbeam-epoch patch

[ryoqun]

Problem

I broke windows build after #26555

   Compiling crossbeam-epoch v0.9.5 (https://github.com/solana-labs/crossbeam?rev=fd279d707025f0e60951e429bf778b4813d1b6bf#fd279d70)
error: expected item, found `..`
 --> C:\Users\runneradmin\.cargo\git\checkouts\crossbeam-2841e3eed153c98b\fd279d7\crossbeam-epoch\no_atomic.rs:1:1
  |
1 | ../no_atomic.rs
  | ^^

error[E0425]: cannot find value `NO_ATOMIC_CAS` in this scope
  --> C:\Users\runneradmin\.cargo\git\checkouts\crossbeam-2841e3eed153c98b\fd279d7\crossbeam-epoch\build.rs:27:8
   |
27 |     if NO_ATOMIC_CAS.contains(&&*target) {
   |        ^^^^^^^^^^^^^ not found in this scope

For more information about this error, try `rustc --explain E0425`.
error: could not compile `crossbeam-epoch` due to 2 previous errors
warning: build failed, waiting for other jobs to finish...
error: build failed

Summary of Changes

Fixes #

[ryoqun]

shellcheck passed. :)

let's see on the master branch... cc: @yihau @willhickey