[Boost-build] Prevent building when exceeding Windows' path length limit

Subject: [Boost-build] Prevent building when exceeding Windows' path length limit
From: Matthew Chambers (matt.chambers42_at_[hidden])
Date: 2011-05-18 11:57:31

Having been bitten a few times by this in the middle of a build - at which point I had to restart 
with --hash - it got me thinking that this should be tested as much as possible before starting the 
action phase. Just run through all the target output paths and make sure they don't exceed MAX_PATH. 
How hard would this be to implement? It won't catch cases inside the actions of custom make targets, 
but it'd catch almost everything.

Thanks,
-Matt