[circt] Bump to d5e356bcc — fix 4 rebase artifacts in 401f5dc8c

Fixes applied on top of 401f5dc8c (fix regressions from #21-#23):
- ImportVerilog.h: restore allowMultiAlwaysCombDrivers + runSlangAnalysis
  (fields removed from header but still used in .cpp files)
- ImportVerilogInternals.h: remove duplicate covergroupImplicitSamplingVars
- Structure.cpp: restore missing closing brace for if (initExpr)
  (caused cascading 'function definition not allowed here' errors)
- LLHDProcessInterpreter.cpp: remove duplicate traceUvmFactoryByType
  (const bool redeclaration of already-declared bool in same scope)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: thomasahle

scripts/toolchain.lock.sh

@@ -7,7 +7,7 @@ readonly NODE_MAJOR_VERSION_LOCKED="22"
 readonly EMSDK_VERSION_LOCKED="4.0.21"
 
 readonly CIRCT_REPO_LOCKED="https://github.com/thomasnormal/circt.git"
-readonly CIRCT_REF_LOCKED="401f5dc8c0f1bc1770c905858a91426071abeb73"
+readonly CIRCT_REF_LOCKED="d5e356bcc3b42a1e9dbadd9f14ae0e7c850be4a0"
 readonly CIRCT_LLVM_SUBMODULE_REF_LOCKED="aa3d6b37c7945bfb4c261dd994689de2a2de25bf"
 
 readonly SURFER_ARTIFACT_URL_LOCKED="https://gitlab.com/surfer-project/surfer/-/jobs/artifacts/main/download?job=pages_build"