Add libc++.1.dylib to the healthcheck whitelist.

This is a standard system package that gecode links to. From pkgutil:

    $ pkgutil --file-info /usr/lib/libc++.1.dylib

    volume: /
    path: /usr/lib/libc++.1.dylib

    pkgid: com.apple.pkg.BaseSystemBinaries
    pkg-version: 10.9.0.1.1.1306847324
    install-time: 1382478239
    uid: 0
    gid: 0
    mode: 755


/cc @opscode/client-eng @opscode/release-engineers