[PATCH] Fix parallel build failure for Texinfo manual

[Ulrich Müller]

* doc/Makefile (org.texi, orgguide.texi): Fix parallel build failure.
---

Forwarding Gentoo Linux bug #829055 <https://bugs.gentoo.org/829055>.
When doing a parallel build (make -j16), a failure was observed when
building the Texinfo documentation:

make -C doc info
make[1]: Entering directory 
'/var/tmp/portage/app-emacs/org-mode-9.5/work/org-mode-release_9.5/doc'
emacs  -Q -batch --eval '(setq vc-handled-backends nil org-startup-folded nil)' 
                                      \
  --eval '(add-to-list `load-path "../lisp")' \
  --eval '(load "../mk/org-fixup.el")'        \
  --eval '(org-make-manuals)'
emacs  -Q -batch --eval '(setq vc-handled-backends nil org-startup-folded nil)' 
                                      \
  --eval '(add-to-list `load-path "../lisp")' \
  --eval '(load "../mk/org-fixup.el")'        \
  --eval '(org-make-manuals)'
Loading 
/var/tmp/portage/app-emacs/org-mode-9.5/work/org-mode-release_9.5/mk/org-fixup.el
 (source)...
Loading 
/var/tmp/portage/app-emacs/org-mode-9.5/work/org-mode-release_9.5/mk/org-fixup.el
 (source)...
...lease_9.5/doc/org.texi locked by portage@local... (pid 55): (s, q, p, ?)? 
Cannot resolve lock conflict in batch mode
make[1]: *** [Makefile:31: orgguide.texi] Error 255
make[1]: *** Waiting for unfinished jobs....
make[1]: Leaving directory 
'/var/tmp/portage/app-emacs/org-mode-9.5/work/org-mode-release_9.5/doc'
make: *** [mk/targets.mk:127: info] Error 2

Fix by making org.texi a prerequisite of orgguide.texi, with an empty
recipe.

 doc/Makefile | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/doc/Makefile b/doc/Makefile
index 96fda1445..7f996deae 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -27,12 +27,14 @@ guide::             orgguide.texi org-version.inc
        ../mk/guidesplit.pl $@/*
 endif
 
-org.texi orgguide.texi:        org-manual.org org-guide.org
+org.texi:      org-manual.org org-guide.org
        $(BATCH) \
          --eval '(add-to-list '"'"'load-path "../lisp")' \
          --eval '(load "../mk/org-fixup.el")' \
          --eval '(org-make-manuals)'
 
+orgguide.texi: org.texi
+
 org-version.inc:       org.texi
        @echo "org-version: $(ORGVERSION) ($(GITVERSION))"
        @echo "@c automatically generated, do not edit"  > org-version.inc
-- 
2.34.1