Integrate LLVM at llvm/llvm-project@9a0b003dde83

Updates LLVM usage to match
[9a0b003dde83](https://github.com/llvm/llvm-project/commit/9a0b003dde83)

PiperOrigin-RevId: 890607352

Integrate LLVM at llvm/llvm-project@3c8e9499ac4c

Updates LLVM usage to match
[3c8e9499ac4c](https://github.com/llvm/llvm-project/commit/3c8e9499ac4c)

PiperOrigin-RevId: 890219804

Add support for passing extra xlscc args through bazel command line.

Using the flag --//xls/contrib/xlscc/config:extra_xls_cc_args=... will add any flags passed directly to the xlscc invocation. No checking will be performed, these will be added directly as strings.

Some refactoring of the xlscc argument construction system is also done to enable this new feature.

PiperOrigin-RevId: 889437793

Integrate LLVM at llvm/llvm-project@31b17c4789ab

Updates LLVM usage to match
[31b17c4789ab](https://github.com/llvm/llvm-project/commit/31b17c4789ab)

PiperOrigin-RevId: 888962167

Replace ABSL_LOC macros with their direct equivalent

PiperOrigin-RevId: 888293329

Integrate LLVM at llvm/llvm-project@a70419505471

Updates LLVM usage to match
[a70419505471](https://github.com/llvm/llvm-project/commit/a70419505471)

PiperOrigin-RevId: 887022209

[codegen 1.5] Improve register cleanup transitive visibility performance

The RegisterCleanupPass now uses a DFS-based reachability test to find all registers that are transitively "visible" (i.e., their values can eventually affect a side-effecting operation), and remove all unnecessary registers. This replaces the previous approach of building a transitive closure graph, which was substantially slower on large graphs; full pairwise reachability was overkill since we only need to know (for each node) whether it can reach anything in a fixed set of sinks.

PiperOrigin-RevId: 886463810

Fix missing includes in c_api_test

PiperOrigin-RevId: 885732382

Integrate LLVM at llvm/llvm-project@e30aa40aa677

Updates LLVM usage to match
[e30aa40aa677](https://github.com/llvm/llvm-project/commit/e30aa40aa677)

PiperOrigin-RevId: 885208509

Add support for dslx/ir-opt rules to specify their own custom pass pi…