resolve: Temporarily make panic available with no_implicit_prelude

[petrochenkov]

Until uses of panic in the standard library are hygienized somehow (#61629).
Closes#61567 (which was introduced by migration or core/std to 2018 edition).

Alternative: Close#61567 as wontfix, this PR is a hack and makes panic available even if it's not nested in a standard macro, and no_implicit_prelude is almost never used in practice, and the proper solution wont' be ready until the release.

[rust-highfive]

r? @estebank

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[estebank]

cc @rust-lang/compiler

What is the behavior when it compiles? Does the correct macro get found (core/std) and run?

[petrochenkov]

What is the behavior when it compiles?

It makes any macro named panic and imported vis #[macro_use] extern crate foo; a resolution candidate in #[no_implicit_prelude] modules.
It isn't guaranteed to be the standard panic, but it's expected to be the standard panic in most cases (assuming the word "most" is applicable to something like #[no_implicit_prelude] at all).

[pnkfelix]

Discussed at T-compiler meeting. Closed #61567 as wont-fix; closing this as wont-land.

[Mark-Simulacrum]

I am de-nominating this from beta -- it seems we're not going ahead with a fix here.