Use arch dispatch workaround on GCC 7-8 as well (#7349)

Fixes: NVBug 5838921

Author: bernhardmgruber

cub/cub/device/dispatch/dispatch_radix_sort.cuh

@@ -1153,8 +1153,8 @@ public:
       return __invoke_single_tile(kernel_source.RadixSortSingleTileKernel(), policy.single_tile);
     }
 
-#if _CCCL_COMPILER(GCC, <, 8)
-    // gcc 7 fails to use `policy` in a constant expression, so we just compute it again inplace
+#if _CCCL_COMPILER(GCC, <, 10)
+    // gcc 7-9 fail to use `policy` in a constant expression, so we just compute it again inplace
     if CUB_DETAIL_CONSTEXPR_ISH (PolicyGetter{}().use_onesweep)
 #else // _CCCL_COMPILER(GCC, <, 8)
     if CUB_DETAIL_CONSTEXPR_ISH (policy.use_onesweep)