Revert versions of autoconf and automake which broke lhapdf compilation.
Merge pull request #920 from cms-sw/downgrade_autoconf_71X

Revert versions of autoconf and automake which broke lhapdf compilation.
Merge remote branch 'origin/IB/CMSSW_7_1_X/stable' into IB/CMSSW_7_0_X/stable