new solver: handle edge case of a recursion limit of 0

Apparently a recursion limit of 0 is possible/valid/useful/used/cute, the more you know 🌟 .

(It's somewhat interesting to me that the old solver seemingly handles this, and that the new solver currently requires a recursion limit of 2 here)

r? `@compiler-errors.`

Fixes rust-lang#115351.

…iaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#113565 (Make SIGSEGV handler emit nicer backtraces)
 - rust-lang#114704 (parser: not insert dummy field in struct)
 - rust-lang#115272 (miri/diagnostics: don't forget to print_backtrace when ICEing on unexpected errors)
 - rust-lang#115313 (Make `get_return_block()` return `Some` only for HIR nodes in body)
 - rust-lang#115347 (suggest removing `impl` in generic trait bound position)
 - rust-lang#115355 (new solver: handle edge case of a recursion limit of 0)
 - rust-lang#115363 (Don't suggest adding parentheses to call an inaccessible method.)

r? `@ghost`
`@rustbot` modify labels: rollup

Fix bors missing a commit when merging rust-lang#115355

bors incorrectly merged an outdated version of PR rust-lang#115355 (via rollup rust-lang#115370):
- it [recorded r+](rust-lang#115355 (comment)) as approving commit rust-lang@325b585, and thus merged the original revision rust-lang@7762ac7
- but the branch at the time was at commit rust-lang@eefa07d, so bors missed the `compiler/rustc_trait_selection/src/solve/search_graph/mod.rs` cleanup in commit rust-lang@0e1e964 😓

Thankfully the change that bors missed was small, and this new PR corrects the situation (as I'd rather avoid having confusing multiple merge commits of PR rust-lang#115355 in the git history)

r? `@compiler-errors`

Fix bors missing a commit when merging rust-lang#115355

bors incorrectly merged an outdated version of PR rust-lang#115355 (via rollup rust-lang#115370):
- it [recorded r+](rust-lang#115355 (comment)) as approving commit rust-lang@325b585, and thus merged the original revision rust-lang@7762ac7
- but the branch at the time was at commit rust-lang@eefa07d, so bors missed the `compiler/rustc_trait_selection/src/solve/search_graph/mod.rs` cleanup in commit rust-lang@0e1e964 😓

Thankfully the change that bors missed was small, and this new PR corrects the situation (as I'd rather avoid having confusing multiple merge commits of PR rust-lang#115355 in the git history)

r? ``@compiler-errors``

…iaskrgr

Rollup of 3 pull requests

Successful merges:

 - rust-lang#115373 (Fix bors missing a commit when merging rust-lang#115355)
 - rust-lang#115378 (`ignore-cross-compile` remaining tests that run binaries)
 - rust-lang#115393 (Make `termcolor` types public in `rustc_errors`)

r? `@ghost`
`@rustbot` modify labels: rollup