patch 8.1.2315: not always using the right window when jumping to an error

Problem:    Not always using the right window when jumping to an error.
Solution:   Add the "uselast" flag in 'switchbuf'. (closes #1652)
diff --git a/src/version.c b/src/version.c
index 8422b71..b6a209d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2315,
+/**/
     2314,
 /**/
     2313,