Fix spacing of pretty printed const item without body

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1116,9 +1116,9 @@ impl<'a> State<'a> {
         self.print_ident(ident);
         self.word_space(":");
         self.print_type(ty);
-        self.space();
         self.end(); // end the head-ibox
         if let Some(body) = body {
+            self.space();
             self.word_space("=");
             self.print_expr(body);
         }

src/test/pretty/issue-68710-field-attr-proc-mac-lost.rs

@@ -7,7 +7,8 @@ struct C {
 }
 
 #[allow()]
-const C: C =
+const C: C
+    =
     C{
       #[cfg(debug_assertions)]
       field: 0,

src/test/ui/macros/stringify.rs

@@ -382,7 +382,7 @@ fn test_item() {
         stringify_item!(
             static S: ();
         ),
-        "static S: () ;", // FIXME
+        "static S: ();",
     );
     assert_eq!(
         stringify_item!(
@@ -402,7 +402,7 @@ fn test_item() {
         stringify_item!(
             const S: ();
         ),
-        "const S: () ;", // FIXME
+        "const S: ();",
     );
 
     // ItemKind::Fn

src/test/ui/proc-macro/quote-debug.stdout

@@ -43,7 +43,8 @@ fn main() {
      crate::TokenStream::from(crate::TokenTree::Punct(crate::Punct::new('\u{3b}',
                                                                         crate::Spacing::Alone)))].iter().cloned().collect::<crate::TokenStream>()
 }
-const _: () =
+const _: ()
+    =
     {
         extern crate proc_macro;
         #[rustc_proc_macro_decls]