[Linux] Add an env var to control XSHM
[Linux] Add an env var to control XSHM

user might want to disable the xshm in fear of leaking shared memory
segments

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