patch 9.0.0634: evaluating "expr" options has more overhead than needed

Problem:    Evaluating "expr" options has more overhead than needed.
Solution:   Use call_simple_func() for 'foldtext', 'includeexpr', 'printexpr',
            "expr" of 'spellsuggest', 'diffexpr', 'patchexpr', 'balloonexpr',
            'formatexpr', 'indentexpr' and 'charconvert'.

src/map.c

@@ -1711,7 +1711,7 @@ eval_map_expr(
     }
 
     // Note: the evaluation may make "mp" invalid.
-    p = eval_to_string(expr, FALSE);
+    p = eval_to_string(expr, FALSE, FALSE);
 
     --textlock;
     --ex_normal_lock;