treat for<'a> T: 'a as T: 'static

[apasel422]

closes #26217

r? @nikomatsakis

[apasel422]

@nikomatsakis I think I implemented this as you suggested to me, but the error message for types that fail the 'static obligation here should be changed, as it is not necessarily obvious how the for<'a> T: 'a predicate becomes 'static. Additionally, in order to make sure the logic is sound, I'm curious how we ultimately might support the following:

fn foo<'a, T>() where for<'b: 'a> T: 'b {}

[nikomatsakis]

@apasel422 well, adding where clauses to for binders is a much larger topic =)

[nikomatsakis]

@bors r+

[bors]

📌 Commit d088db9 has been approved by nikomatsakis

[bors]

⌛ Testing commit d088db9 with merge a27fed7...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt

[apasel422]

What issues should I open as follow-ups to this PR?