Fix ambiguous precedences in tests

Author: Urgau

tests/rustdoc/const-generics/const-generics-docs.rs

@@ -74,7 +74,7 @@ pub async fn b_sink<const N: usize>(_: impl Trait<N>) {}
 
 // @has foo/fn.concrete.html '//pre[@class="rust item-decl"]' \
 //      'pub fn concrete() -> [u8; 22]'
-pub fn concrete() -> [u8; 3 + std::mem::size_of::<u64>() << 1] {
+pub fn concrete() -> [u8; (3 + std::mem::size_of::<u64>()) << 1] {
     Default::default()
 }
 

tests/ui/consts/const-err-rpass.rs

@@ -9,7 +9,7 @@ const W: bool = Z <= 'B';
 
 
 fn main() {
-    let _ = ((-1 as i8) << 8 - 1) as f32;
+    let _ = ((-1 as i8) << (8 - 1)) as f32;
     let _ = 0u8 as char;
     let _ = true > false;
     let _ = true >= false;