Auto merge of #90392 - solid-rs:fix-solid-support, r=Mark-Simulacrum

kmc-solid: Fix SOLID target

This PR is a follow-up for #86191 and necessary to make the [`*-kmc-solid_*`](https://doc.rust-lang.org/nightly/rustc/platform-support/kmc-solid.html) Tier 3 targets actually usable.

 - Bumps `libc` to 0.2.106, which includes <https://github.com/rust-lang/libc/pull/2227>.
 - Applies the change made by #89324 to this target's target-specific code.

library/std/src/sys/itron/thread.rs

@@ -347,6 +347,6 @@ unsafe fn terminate_and_delete_current_task() -> ! {
     unsafe { crate::hint::unreachable_unchecked() };
 }
 
-pub fn available_concurrency() -> io::Result<crate::num::NonZeroUsize> {
+pub fn available_parallelism() -> io::Result<crate::num::NonZeroUsize> {
     super::unsupported()
 }