make tags: index also Modules/_ctypes/ (#4648) (#4660)

Avoid also "cd $(srcdir)" to not change the current directory.

(cherry picked from commit 3be3b97a)

Makefile.pre.in

@@ -1378,10 +1378,9 @@ autoconf:
 
 # Create a tags file for vi
 tags::
-	cd $(srcdir); \
-	ctags -w Include/*.h; \
-	for i in $(SRCDIRS); do ctags -f tags -w -a $$i/*.[ch]; \
-	done; \
+	ctags -w $(srcdir)/Include/*.h
+	for i in $(SRCDIRS); do ctags -f tags -w -a $(srcdir)/$$i/*.[ch]; done
+	ctags -f tags -w -a $(srcdir)/Modules/_ctypes/*.[ch]
 	LC_ALL=C sort -o tags tags
 
 # Create a tags file for GNU Emacs