Remove "manual" label from test targets that can be run within a reas…

VisibilityAnalysis improvements:

* new SingleSelectVisibilityAnalysis that tries to produce a visibility expression derived from edges on a single priority select.
* VisibilityAnalysis now prunes visibility edges if BDD saturation is hit on the full expression.
* VisibilityAnalysis now falls back on conservatively assuming visibility is equal to the nearest understood post dominator if pruning edges also fails.

PiperOrigin-RevId: 839944075

[std] Let users access `apfloat::raw_mul` directly

This is usually not the right plan - it requires taking over responsibility for the ways `raw_mul` produces an unfinished result - but some applications call for direct manipulation of the intermediate floating-point value.

PiperOrigin-RevId: 839430508

Add stub synth_only headers for cstring, stdlib.h, and tuple.

These headers allow xlscc to parse C++ code that includes <cstring>, <stdlib.h>, and <tuple>, without providing any synthesizable functionality.

PiperOrigin-RevId: 838993421

[codegen 1.5] Implement BlockFinalizationPass, converting ScheduledBl…

Fix OSS build

PiperOrigin-RevId: 836806997

Integrate LLVM at llvm/llvm-project@dea330b38d9c

Updates LLVM usage to match
[dea330b38d9c](https://github.com/llvm/llvm-project/commit/dea330b38d9c)

PiperOrigin-RevId: 836460028

Integrate LLVM at llvm/llvm-project@f2cb5d7a05ba

Updates LLVM usage to match
[f2cb5d7a05ba](https://github.com/llvm/llvm-project/commit/f2cb5d7a05ba)

PiperOrigin-RevId: 835980399

Allow the available area and delay models to be controlled by toolcha…

Minimize flakiness and address actual MSAN mismatches in function_jit…