patch 9.1.0810: cannot easily adjust the |:find| command

Problem:  cannot easily adjust the |:find| command
Solution: Add support for the 'findexpr' option (Yegappan Lakshmanan)

closes: #15901
closes: #15905

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/structs.h b/src/structs.h
index e4a79f5..39e60a4 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -3327,6 +3327,9 @@
     char_u	*b_p_efm;	// 'errorformat' local value
 #endif
     char_u	*b_p_ep;	// 'equalprg' local value
+#ifdef FEAT_EVAL
+    char_u	*b_p_fexpr;	// 'findexpr' local value
+#endif
     char_u	*b_p_path;	// 'path' local value
     int		b_p_ar;		// 'autoread' local value
     char_u	*b_p_tags;	// 'tags' local value