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/if_perl.xs b/src/if_perl.xs
index ab2917a..0241c31 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -873,7 +873,8 @@
     char_u *
 eval_to_string(
     char_u	*arg UNUSED,
-    int		dolist UNUSED)
+    int		convert UNUSED,
+    int		use_simple_function UNUSED)
 {
     return NULL;
 }
@@ -1599,7 +1600,7 @@
     PREINIT:
 	char_u *value;
     PPCODE:
-	value = eval_to_string((char_u *)str, TRUE);
+	value = eval_to_string((char_u *)str, TRUE, FALSE);
 	if (value == NULL)
 	{
 	    XPUSHs(sv_2mortal(newSViv(0)));