sync/atomic: don't run 64-bit uintptr tests on 32-bit systems

The tests don't work on big-endian systems. This change handles more
of the tests added in CL 381317 like the other existing tests.

Fixes #52723

Change-Id: Ie9e048e75dbe0b5aca61b51cd0c50d7d878ff6d6
Reviewed-on: https://go-review.googlesource.com/c/go/+/404495
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>

Author: ianlancetaylor

Diff for: src/sync/atomic/atomic_test.go

@@ -1787,8 +1787,11 @@ func init() {
 	if uintptr(v) == 0 {
 		// 32-bit system; clear uintptr tests
 		delete(hammer64, "SwapUintptr")
+		delete(hammer64, "SwapUintptrMethod")
 		delete(hammer64, "AddUintptr")
+		delete(hammer64, "AddUintptrMethod")
 		delete(hammer64, "CompareAndSwapUintptr")
+		delete(hammer64, "CompareAndSwapUintptrMethod")
 	}
 }