Link: #4928

This was causing a failure in prep-semver-baseline.sh for the daily
cache-building job since there is no base for jobs that run on a branch.

(backport <#4960>)
(cherry picked from commit 708aa56)

Bumps [vmactions/solaris-vm](https://github.com/vmactions/solaris-vm) from 1.2.8 to 1.3.0.
- [Release notes](https://github.com/vmactions/solaris-vm/releases)
- [Commits](vmactions/solaris-vm@v1.2.8...v1.3.0)

---
updated-dependencies:
- dependency-name: vmactions/solaris-vm
  dependency-version: 1.3.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

(backport <#4962>)
(cherry picked from commit f908e86)

Signed-off-by: Anhad Singh <[email protected]>

(backport <#4968>)
(cherry picked from commit 5a68089)

Signed-off-by: Anhad Singh <[email protected]>

(backport <#4968>)
(cherry picked from commit c6900b7)

Add the `tgkill(tgid, tid, sig)` wrapper

(backport <#4970>)
(cherry picked from commit c659e29)

The LLVM bump to resolve this is available in nightlies from the past
couple of days.

This reverts commit e98800a.

(backport <#4971>)
(cherry picked from commit 42cb72d)

compiler-builtins has been fixed such that this is no longer needed.

This reverts commit 5a9e1db.

Link: rust-lang/compiler-builtins#1066

(backport <#4971>)
(cherry picked from commit e79f46e)

Similar to the previous commit, re-enable hexagon docs builds.

This reverts commit 77e9d06.

(backport <#4971>)
(cherry picked from commit e9f75f8)

Add new tier 2 targets to verify-build.py that have shown up since the
last update, and sync the docs.rs target list to it.

In particular, this adds the ohos targets which are tier 2 but were not
documented.

(backport <#4971>)
(cherry picked from commit c57615d)

(backport <#4969>)
(cherry picked from commit c12def3)