make some tests not need output (so they work on wasm)

Author: RalfJung

src/tools/miri/tests/pass/align_offset_symbolic.rs

@@ -62,7 +62,10 @@ fn test_from_utf8() {
     const N: usize = 10;
     let vec = vec![0x4141414141414141u64; N];
     let content = unsafe { std::slice::from_raw_parts(vec.as_ptr() as *const u8, 8 * N) };
-    println!("{:?}", std::str::from_utf8(content).unwrap());
+    assert_eq!(
+        std::str::from_utf8(content).unwrap(),
+        "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
+    );
 }
 
 fn test_u64_array() {

src/tools/miri/tests/pass/align_offset_symbolic.stdout

@@ -31,8 +31,8 @@ fn main() {
     }
 
     // Regression test for Debug impl's
-    println!("{:?} {:?}", dst, dst.iter());
-    println!("{:?}", VecDeque::<u32>::new().iter());
+    format!("{:?} {:?}", dst, dst.iter());
+    format!("{:?}", VecDeque::<u32>::new().iter());
 
     for a in dst {
         assert_eq!(*a, 2);