Remove no-prefer-dynamic from valgrind tests

src/test/run-pass-valgrind/cast-enum-with-dtor.rs

@@ -1,5 +1,3 @@
-// no-prefer-dynamic
-
 #![allow(dead_code)]
 
 // check dtor calling order when casting enums.

src/test/run-pass-valgrind/cleanup-auto-borrow-obj.rs

@@ -1,5 +1,3 @@
-// no-prefer-dynamic
-
 // This would previously leak the Box<Trait> because we wouldn't
 // schedule cleanups when auto borrowing trait objects.
 // This program should be valgrind clean.

src/test/run-pass-valgrind/cleanup-stdin.rs

@@ -1,5 +1,3 @@
-// no-prefer-dynamic
-
 fn main() {
  let _ = std::io::stdin();
  let _ = std::io::stdout();

src/test/run-pass-valgrind/down-with-thread-dtors.rs

@@ -1,4 +1,3 @@
-// no-prefer-dynamic
 // ignore-emscripten
 
 thread_local!(static FOO: Foo = Foo);

src/test/run-pass-valgrind/dst-dtor-1.rs

@@ -1,5 +1,3 @@
-// no-prefer-dynamic
-
 static mut DROP_RAN: bool = false;
 
 struct Foo;

src/test/run-pass-valgrind/dst-dtor-2.rs

@@ -1,5 +1,3 @@
-// no-prefer-dynamic
-
 static mut DROP_RAN: isize = 0;
 
 struct Foo;

src/test/run-pass-valgrind/dst-dtor-3.rs

@@ -1,5 +1,3 @@
-// no-prefer-dynamic
-
 #![feature(unsized_tuple_coercion)]
 
 static mut DROP_RAN: bool = false;

src/test/run-pass-valgrind/dst-dtor-4.rs

@@ -1,5 +1,3 @@
-// no-prefer-dynamic
-
 #![feature(unsized_tuple_coercion)]
 
 static mut DROP_RAN: isize = 0;

src/test/run-pass-valgrind/exit-flushes.rs

@@ -1,4 +1,3 @@
-// no-prefer-dynamic
 // ignore-cloudabi
 // ignore-emscripten
 // ignore-sgx no processes

src/test/run-pass-valgrind/osx-frameworks.rs

@@ -1,4 +1,3 @@
-// no-prefer-dynamic
 // pretty-expanded FIXME #23616
 
 #![feature(rustc_private)]