test: updated expected Vec src path

src/test/ui/associated-types/defaults-wf.stderr

@@ -4,7 +4,7 @@ error[E0277]: the size for values of type `[u8]` cannot be known at compilation
 LL |     type Ty = Vec<[u8]>;
    |     ^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    | 
-  ::: $SRC_DIR/alloc/src/vec.rs:LL:COL
+  ::: $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
    |
 LL | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
    |                - required by this bound in `Vec`

src/test/ui/bad/bad-sized.stderr

@@ -15,7 +15,7 @@ error[E0277]: the size for values of type `dyn Trait` cannot be known at compila
 LL |     let x: Vec<dyn Trait + Sized> = Vec::new();
    |            ^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    | 
-  ::: $SRC_DIR/alloc/src/vec.rs:LL:COL
+  ::: $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
    |
 LL | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
    |                - required by this bound in `Vec`

src/test/ui/issues/issue-20433.stderr

@@ -4,7 +4,7 @@ error[E0277]: the size for values of type `[i32]` cannot be known at compilation
 LL |     fn iceman(c: Vec<[i32]>) {}
    |                  ^^^^^^^^^^ doesn't have a size known at compile-time
    | 
-  ::: $SRC_DIR/alloc/src/vec.rs:LL:COL
+  ::: $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
    |
 LL | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
    |                - required by this bound in `Vec`

src/test/ui/lint/lint-const-item-mutation.stderr

@@ -107,7 +107,7 @@ LL |     VEC.push(0);
    = note: each usage of a `const` item creates a new temporary
    = note: the mutable reference will refer to this temporary, not the original `const` item
 note: mutable reference created due to call to this method
-  --> $SRC_DIR/alloc/src/vec.rs:LL:COL
+  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
    |
 LL | /     pub fn push(&mut self, value: T) {
 LL | |         // This will panic or abort if we would allocate > isize::MAX bytes