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/optionstr.c b/src/optionstr.c
index 143c8dd..b63a351 100644
--- a/src/optionstr.c
+++ b/src/optionstr.c
@@ -39,7 +39,8 @@
     "localoptions", "options", "help", "blank", "globals", "slash", "unix",
     "sesdir", "curdir", "folds", "cursor", "tabpages", "terminal", NULL};
 #endif
-static char *(p_swb_values[]) = {"useopen", "usetab", "split", "newtab", "vsplit", NULL};
+// Keep in sync with SWB_ flags in option.h
+static char *(p_swb_values[]) = {"useopen", "usetab", "split", "newtab", "vsplit", "uselast", NULL};
 static char *(p_tc_values[]) = {"followic", "ignore", "match", "followscs", "smart", NULL};
 #if defined(FEAT_TOOLBAR) && !defined(FEAT_GUI_MSWIN)
 static char *(p_toolbar_values[]) = {"text", "icons", "tooltips", "horiz", NULL};