rustc_codegen_ssa: Remove trailing spaces in Display impl for CguReuse

Otherwise errors will look like this:

    error: CGU-reuse for `cgu_invalidated_via_import-bar` is `PreLto ` but should be `PostLto `

compiler/rustc_codegen_ssa/src/assert_module_sources.rs

@@ -199,8 +199,8 @@ impl fmt::Display for CguReuse {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
             CguReuse::No => write!(f, "No"),
-            CguReuse::PreLto => write!(f, "PreLto "),
-            CguReuse::PostLto => write!(f, "PostLto "),
+            CguReuse::PreLto => write!(f, "PreLto"),
+            CguReuse::PostLto => write!(f, "PostLto"),
         }
     }
 }