bug#30631: Automake 1.6 fails to build with perl 5.18.2

[Andreas Schwab]

I get this build failure when building automake 1.6 with perl 5.18.2:

$ make -j4
  GEN      bin/automake
  GEN      bin/aclocal
  GEN      t/ax/shell-no-trail-bslash
  GEN      t/ax/cc-no-c-o
  GEN      runtest
  GEN      doc/aclocal.1
  GEN      doc/automake.1
  GEN      lib/Automake/Config.pm
  GEN      t/ax/test-defs.sh
  GEN      bin/aclocal-1.16
  GEN      bin/automake-1.16
  GEN      doc/aclocal-1.16.1
  GEN      doc/automake-1.16.1
help2man: can't get `--help' info from automake-1.16
Try `--no-discard-stderr' if option outputs to stderr
Makefile:3694: recipe for target 'doc/automake-1.16.1' failed
make: *** [doc/automake-1.16.1] Error 255
make: *** Waiting for unfinished jobs....

$ ./pre-inst-env automake-1.16 --help
"none" is not exported by the List::Util module
Can't continue after import errors at 
/home/abuild/rpmbuild/BUILD/automake-1.16/bin/automake-1.16 line 76.
BEGIN failed--compilation aborted at 
/home/abuild/rpmbuild/BUILD/automake-1.16/bin/automake-1.16 line 76.

Andreas.

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Andreas Schwab, address@hidden
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