Fix stale ODR-use state before lexed inline methods

[AnastaZIuk]

Summary

This clears stale delayed ODR-use bookkeeping before starting a lexed inline method body.

It also adds a small SPIR-V regression test for the same parser path.

Root cause

The missing cleanup is in ParseLexedMethodDef, which was introduced in 6ee4074a4.

That path enters ActOnStartOfFunctionDef(...) without first calling CleanupVarDeclMarking().

HLSL constant-expression references inside declarations such as [[vk::binding(Bindings::Mask, SessionDSIndex)]] can leave entries in MaybeODRUseExprs.

When the next lexed inline method is parsed, ActOnFinishFunctionBody(...) trips the debug invariant:

Leftover expressions for odr-use checking

Impact

This crashes assert-enabled DXC builds on valid HLSL.

Public release-like builds usually compile the same source because assertions are off, so the bug is masked rather than absent.

Repros

• Original immutable input from NSC -P: godbolt.org/z/81nsEja1v
• New minimized repro now checked into tools/clang/test/CodeGenSPIRV/ex40-lexed-inline-method-odr-use-crash.hlsl: godbolt.org/z/3zfraP9bf

Both CE links use the public dxc_trunk build, so they compile there because that build does not expose the local debug assert path.