[boost] Request permission to apply patch to trunk.

I'd like to apply the attached patch to trunk. It is not supposed to break anything on an svn checkout, but we held off applying it until 1.55 beta shipped because of concern it would be disruptive if it somehow messed up the build system right in the middle of getting the beta out. Thanks to Bjørn Roald for developing the patch. Without this patch, the only way to test modular-boost headers mechanism is to manually apply the patch yourself, and that pretty much limits testing. OK to apply? --Beman