Merge branch 'master' into ng/master

* master:
  build: use slightly older help2man, for improved portability
  tests: avoid spurious failure when 'install-info' program is unavailable
  install: shell parameter expansions can be used in directory names
  test defs: more environment cleanups
  test defs: unset 'AM_UPDATE_INFO_DIR' environment variable
  build: generate doc/*.1 files; include help2man
  build: avoid parallel build failures

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

diff --cc Makefile.am
Simple merge

diff --cc configure.ac
Simple merge

diff --cc defs
Simple merge