Mark expr_requires_semi_to_be_stmt call sites

For each of these, we need to decide whether they need to be using
`expr_requires_semi_to_be_stmt`, or `expr_requires_comma_to_be_match_arm`,
which are supposed to be 2 different behaviors. Previously they were
conflated into one, causing either too much or too little
parenthesization.

compiler/rustc_lint/src/unused.rs

@@ -688,7 +688,7 @@ trait UnusedDelimLint {
                     ExprKind::Index(base, _subscript, _) => base,
                     _ => break,
                 };
-                if !classify::expr_requires_semi_to_be_stmt(innermost) {
+                if !classify::expr_requires_semi_to_be_stmt_FIXME(innermost) {
                     return true;
                 }
             }