gnulib: bump minimum supported autoconf version

1 job for rdm/update-dependencies in 7 minutes and 3 seconds
Status Job ID Name Coverage
  Test
failed #103876
debian-stable-gcc

00:07:03

 
Name Stage Failure
failed
debian-stable-gcc Test
make[3]: Nothing to be done for 'all-am'.
make[3]: Leaving directory '/builds/tiger/nolimips/distrib'
make[2]: Leaving directory '/builds/tiger/nolimips/distrib'
make[2]: Entering directory '/builds/tiger/nolimips'
make[2]: Leaving directory '/builds/tiger/nolimips'
make[1]: Leaving directory '/builds/tiger/nolimips'
make[1]: *** [Makefile:461: all-recursive] Error 1
make: *** [Makefile:391: all] Error 2
ERROR: Job failed: exit code 1