libsm-dev binary package in Ubuntu Xenial amd64

 This package provides the main interface to the X11 Session Management
 library, which allows for applications to both manage sessions, and make use
 of session managers to save and restore their state for later use.
 .
 This package contains the development headers for the library found in libsm6.
 Non-developers likely have little use for this package.
 .
 More information about X.Org can be found at:
 <URL:http://www.X.org>
 .
 This module can be found at
 git://anongit.freedesktop.org/git/xorg/lib/libSM

Source package