[Rivet] Boost foreach bug

[David Grellscheid]

Hi all,

I have just added a check for a nasty foreach bug in Boost which broke
some Rivet analyses. gcc versions >=4.6 require boost >=1_47 to make
BOOST_FOREACH work properly.

http://code-muse.com/2013/08/06/boostforeach-and-compiler-bugs

The main affected system is Ubuntu 12.04, which by default ships a
broken combination of gcc-4.6 and boost-1_46. The packages will not
compile anymore with this setup.

See you,

  David