Don't run instanceof test on 4.17

tests/UnusedUseClauseLinterTest.hack

@@ -9,6 +9,8 @@
 
 namespace Facebook\HHAST;
 
+use namespace HH\Lib\Vec;
+
 final class UnusedUseClauseLinterTest extends TestCase {
   use AutoFixingLinterTestTrait<ASTLintError>;
 
@@ -17,9 +19,8 @@ final class UnusedUseClauseLinterTest extends TestCase {
   }
 
   public function getCleanExamples(): vec<(string)> {
-    return vec[
+    $base = vec[
       tuple("<?hh\nuse type Foo; Foo::bar();"),
-      tuple("<?hh\nuse type Foo; \$x instanceof Foo;"),
       tuple("<?hh\nuse type Foo; function bar<T as Foo>(): void {}"),
       tuple("<?hh\nuse type Foo; class Bar<T as Foo>{}"),
       tuple("<?hh\nuse type Foo; new Foo();"),
@@ -32,5 +33,12 @@ final class UnusedUseClauseLinterTest extends TestCase {
       tuple("<?hh\nuse function foo; foo();"),
       tuple("<?hh\nuse const FOO; var_dump(FOO);"),
     ];
+
+    if (\HHVM_VERSION_ID >= 41700) {
+      return $base;
+    }
+    return Vec\concat($base, vec[
+      tuple("<?hh\nuse type Foo; \$x instanceof Foo;"),
+    ]);
   }
 }