Build fails on Centos 6.5: charlock holmes links to system libz
$ find /opt -name file | grep charl | xargs ldd
/opt/gitlab/embedded/service/gem/ruby/1.9.1/gems/charlock_holmes-0.6.9.4/ext/charlock_holmes/dst/bin/file:
linux-vdso.so.1 => (0x00007fffd10e1000)
libz.so.1 => /lib64/libz.so.1 (0x00007fb164d63000)
libc.so.6 => /lib64/libc.so.6 (0x00007fb1649cf000)
/lib64/ld-linux-x86-64.so.2 (0x00007fb164f81000)
/opt/gitlab/embedded/service/gem/ruby/1.9.1/gems/charlock_holmes-0.6.9.4/ext/charlock_holmes/src/file-5.08/src/file:
linux-vdso.so.1 => (0x00007fff79c7e000)
libz.so.1 => /lib64/libz.so.1 (0x00007f8510ccf000)
libc.so.6 => /lib64/libc.so.6 (0x00007f851093b000)
/lib64/ld-linux-x86-64.so.2 (0x00007f8510eed000)
This makes the omnibus-ruby health check fail.