Add x86-linux-release community triplet

[dpogue]

Following up on #28943 in the spirit of #22120 & #28525, this adds a x86-linux-release community triplet to match the existing x86-linux triplet.

[autoantwort]

Does this apply? #29034 (comment)

[autoantwort]

We will add community triplets if:

• It is demonstrated that people will actually use that community triplet; and,
• we don't know that such a triplet is broken.

[dpogue]

Ah, yep, that probably does apply. I was just adding this for consistency with the other *-linux-release triplets, but if there is a desire to focus on community triplets with demonstable use then this can probably wait until someone makes a compelling case to add it.

Thanks for flagging that.