patch 8.2.4943: changing 'switchbuf' may have no effect

Problem:    Changing 'switchbuf' may have no effect.
Solution:   Handle 'switchbuf' in didset_string_options(). (Sean Dewar,
            closes #10406)
diff --git a/src/version.c b/src/version.c
index 480acfd..0ebc9cb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4943,
+/**/
     4942,
 /**/
     4941,