[Linux] Free any remaining shm segments
[Linux] Free any remaining shm segments

Some of compositors don't have a chance to be destroyed when the
application quits, which will result in some leaked shared memory
segment.

Pointillistic/rebol-lang,zsx/r3,zsx/r3,Pointillistic/rebol-lang,Pointillistic/rebol-lang,Pointillistic/rebol-lang,zsx/r3,zsx/r3