Update compiler/rustc_metadata/src/rmeta/mod.rs

Co-authored-by: bjorn3 <bjorn3@users.noreply.github.com>

Author: cjgillot

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -51,7 +51,7 @@ const METADATA_VERSION: u8 = 5;
 /// This header is followed by the position of the `CrateRoot`,
 /// which is encoded as a 32-bit big-endian unsigned integer,
 /// and further followed by the rustc version string.
-pub const METADATA_HEADER: &[u8; 8] = &[b'r', b'u', b's', b't', 0, 0, 0, METADATA_VERSION];
+pub const METADATA_HEADER: &[u8] = &[b'r', b'u', b's', b't', 0, 0, 0, METADATA_VERSION];
 
 /// Additional metadata for a `Lazy<T>` where `T` may not be `Sized`,
 /// e.g. for `Lazy<[T]>`, this is the length (count of `T` values).