KenLM 5cc905bc2d214efa7de2db56a9a672b749a95591

Avoid unspecified behavior of mmap when a file is resized reported by Christian Hardmeier
Fixes for Mavericks and a workaround for Boost's broken semaphore
Clean clang compile (of kenlm)

Merged some of 744376b3fbebc41c4a270bf549826d5eb9219ae0 but also undid some of it because it was just masking a fundaemntal problem with pread rather than working around windows limitations