Ignore the cmath-fix block on non-vs compilers.

git-svn-id: http://svn.code.sf.net/p/vcmi/code/trunk/@3434 4dfc6b2a-8b31-0410-aa91-d6c70e3ac834
Compile fixes specific for VS 2012"
 * Reverted std::bind to boost::bind. std::bind on Visual 2012 doesn't work in some cases (especially with std::ref), not sure why [but it seems to be a bug, since 2013 preview compiles the same code fine]. 
 * Move assignment operator for VS 2012.

git-svn-id: http://svn.code.sf.net/p/vcmi/code/trunk/@3435 4dfc6b2a-8b31-0410-aa91-d6c70e3ac834