patch 8.1.2239: CI fails when running tests without building Vim

Problem:    CI fails when running tests without building Vim.
Solution:   Skip creating doc tags if the execute does not exist.
diff --git a/runtime/doc/Makefile b/runtime/doc/Makefile
index 443a27a..57aec4e 100644
--- a/runtime/doc/Makefile
+++ b/runtime/doc/Makefile
@@ -323,7 +323,8 @@
 # Use Vim to generate the tags file.  Can only be used when Vim has been
 # compiled and installed.  Supports multiple languages.
 vimtags: $(DOCS)
-	$(VIMEXE) -eX -u doctags.vim
+	@if test -x $(VIMEXE); then $(VIMEXE) -eX -u doctags.vim; \
+		else echo "vim executable $(VIMEXE) not found"; fi
 
 # Use "doctags" to generate the tags file.  Only works for English!
 tags: doctags $(DOCS)
diff --git a/src/version.c b/src/version.c
index e1d5c64..d0f62e9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2239,
+/**/
     2238,
 /**/
     2237,