Fixes rust-lang#130172

Operations like is_aligned would return actively wrong results at compile-time,
i.e. calling it on the same pointer at compiletime and runtime could yield
different results. That's no good.

Instead of having hacks to make align_offset kind-of work in const-eval, just
use const_eval_select in the few places where it makes sense, which also ensures
those places are all aware they need to make sure the fallback behavior is
consistent.

The target name can be anything with custom target specs. Matching on
fields inside the target spec is much more robust than matching on the
target name.

It is unused.

…=workingjubilee

Generate correct symbols.o for sparc-unknown-none-elf

This fixes rust-lang#130172 by selecting the correct ELF Machine type for sparc-unknown-none-elf (which has a baseline of SPARC V7).

…r=dtolnay

remove const-support for align_offset and is_aligned

As part of the recent discussion to stabilize `ptr.is_null()` in const context, the general vibe was that it's okay for a const function to panic when the same operation would work at runtime (that's just a case of "dynamically detecting that something is not supported as a const operation"), but it is *not* okay for a const function to just return a different result.

Following that, `is_aligned` and `is_aligned_to` have their const status revoked in this PR, since they do return actively wrong results at const time. In the future we can consider having a new intrinsic or so that can check whether a pointer is "guaranteed to be aligned", but the current implementation based on `align_offset` does not have the behavior we want.

In fact `align_offset` itself behaves quite strangely in const, and that support needs a bunch of special hacks. That doesn't seem worth it. Instead, the users that can fall back to a different implementation should just use const_eval_select directly, and everything else should not be made const-callable. So this PR does exactly that, and entirely removes const support for align_offset.

Closes some tracking issues by removing the associated features:
Closes rust-lang#90962
Closes rust-lang#104203

Cc `@rust-lang/wg-const-eval` `@rust-lang/libs-api`

…, r=workingjubilee

Reduce dependence on the target name

The target name can be anything with custom target specs. Matching on fields inside the target spec is much more robust than matching on the target name.

Also remove the unused is_builtin target spec field.

…=nnethercote

remove attribute ids from hir stats (they're simply not needed)

Turns out these are simply not needed. Yay!

r? `@nnethercote`