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'.
diff --git a/src/clientserver.c b/src/clientserver.c
index eaaba25..63aec10 100644
--- a/src/clientserver.c
+++ b/src/clientserver.c
@@ -86,7 +86,7 @@
     // to be typed.  Do generate errors so that try/catch works.
     ++emsg_silent;
 
-    res = eval_to_string(expr, TRUE);
+    res = eval_to_string(expr, TRUE, FALSE);
 
     debug_break_level = save_dbl;
     redir_off = save_ro;