[Dune] build failed in dune-common

[Andreas Dedner]

Hi,
rev 5834 breaks building in dune-common:
--> writing dependencies.m4
    for dune-common 1.3svn dune at dune-project.org
        requires
--> aclocal...
--> autoheader...
--> automake...
--> autoconf...
configure:22403: error: possibly undefined macro: AS_VAR_APPEND
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
--- Failed to build dune-common ---
autoconf --version: autoconf (GNU Autoconf) 2.63
Going back a revision works.
Best
Andreas