po/Makefile.in.in does not support install-pdf and others

[Akim Demaille]

Hi!

A few years ago we were reported that Bison’s install-pdf
target fails because po/’s Makefile does not support it:

http://lists.gnu.org/archive/html/bug-bison/2012-04/msg00011.html

Paul installed a workaround in gnulib itself
(commit 88b94265b630cfcec39dafe954affcee03e36f72), but in
f2f698092426d2fcb69beb184d92d177adc328bf (2015), an update from
gettext to gnulib removed that.  As a consequence, we have the
very same bug report back in Bison
(http://lists.gnu.org/archive/html/bug-bison/2018-06/msg00000.html).

Could 88b94265b630cfcec39dafe954affcee03e36f72 be cherry-picked
in both gnulib and gettext?

Thanks!