Add warning about Apple's weird Clang version.
Print warning on OSX when using old libstdc++ (rather than libc++).
Merge branch 'master' of https://github.com/kentonv/capnproto
Automatically add -stdlib=libc++ if system C++ library doesn't support C++11 (needed on OSX).
Document how to build on OSX.
More Mac notes.
Add note about installing autotools.
Mention how to get Xcode cli tools.
Fix comment.
Merge branch 'master' into benchmark
Don't document inlines.
Merge remote-tracking branch 'upstream/master' into benchmark