Generate ceph-osd-prestart.sh paths in upstart/systemd configs at build time
Ceph version 11.2.0
After `make install`, ceph-osd-prestart.sh will be installed in /usr/libexec/ceph. However, both ceph-osd.conf (upstart config) and ceph-osd@.service (systemd config) run /usr/lib/ceph/ceph-osd-prestart.sh as the pre-start script.
Also, debian/rules uses "-DCMAKE_INSTALL_LIBEXECDIR=/usr/lib" to install it in /usr/lib/ceph, but I guess it's only a workaround.
I don't know if ceph_common.sh has similar problems?