Fixes automake bug https://bugs.gnu.org/30172.
No problem seen by me. Thanks.
- bug#30172: dvi, ps, and pdf targets use AM_MAKEINFOFLAGS Mathieu Lirzin
- bug#30172: dvi, ps, and pdf targets use AM_MAKEINFOFLA... Mike Frysinger
- bug#30172: [PATCH] tests: do not assume AM_MAKEINFOHTM... Mike Frysinger
- bug#30172: [PATCH] tests: do not assume AM_MAKEINF... Karl Berry
