add safeguard for qt4's moc to skip boost header

It is a well-known problem qt4's moc can't handle
preprocessor variables and therefore breaks at a number of places
with boost. Boost 1.57 added one more that makes it impossible to
have ogre includes in code moc has to process....
Merge pull request #1 from v4hn/boost-157-moc

add safeguard for qt4's moc to skip boost header