platform: the huge pages test skips where the kernel or emulator has no such switch

src/platform/huge_pages.zig

@@ -29,7 +29,12 @@ pub fn disable() DisableError!void {
 }
 
 test "disable takes effect for the process" {
-    try disable();
+    disable() catch |err| switch (err) {
+        // qemu-user, which runs the aarch64 suite, rejects the option the way
+        // a pre-3.15 kernel does.
+        error.Unsupported => return error.SkipZigTest,
+        error.Unexpected => return err,
+    };
     const rc = linux.prctl(@intFromEnum(linux.PR.GET_THP_DISABLE), 0, 0, 0, 0);
     try std.testing.expectEqual(linux.E.SUCCESS, linux.errno(rc));
     try std.testing.expectEqual(@as(usize, 1), rc);