patch 8.1.2247: "make vimtags" does not work in runtime/doc

Problem:    "make vimtags" does not work in runtime/doc.
Solution:   Test existence with "which" instead of "test -x". (Ken Takata)
diff --git a/runtime/doc/Makefile b/runtime/doc/Makefile
index 0cbe020..cec670b 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)
-	@if test -x $(VIMEXE); then $(VIMEXE) --clean -eX -u doctags.vim; \
+	@if which $(VIMEXE) >/dev/null; then \
+		$(VIMEXE) --clean -eX -u doctags.vim >/dev/null; \
 		else echo "vim executable $(VIMEXE) not found"; fi
 
 # Use "doctags" to generate the tags file.  Only works for English!
diff --git a/src/version.c b/src/version.c
index 5089d7d..6289798 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2247,
+/**/
     2246,
 /**/
     2245,