test(windows-drivers): adapter-init isolated to wdk-sys IddCx binding (Rust IddCx PROVEN to work on-box)

DECISIVE: installed the pre-built UPSTREAM virtual-display-rs (Rust wdf-umdf IddCx)
driver on the SAME box -> Status=OK. So a Rust IddCx driver inits an adapter here,
self-signed, right now. My wdk-sys driver still fails ONLY at IddCxAdapterInitAsync
(0xc000000d) despite matching virtual-display-rs on EVERY inspectable dimension:
- same iddcx 1.10 headers+stub
- IDDCX_ADAPTER_CAPS + IDD_CX_CLIENT_CONFIG byte-perfect (offsets match C header)
- runtime pointers all valid/non-null (names .rdata, version stack, dev handle)
- identical IddFunctions[idx]+IddDriverGlobals dispatch; indices 0/1/2
- matched the minimal link (tested vendored wdk-build WITHOUT OneCoreUAP/
  NODEFAULTLIB/OPT/INTEGRITYCHECK -> still fails; export pollution ruled out)
- device context, no device interface (control via EvtIddCxDeviceIoControl), init order

The IddCx ClassExtension ETW provider emits no decodable reason (WPP/kernel-debugger
only). The remaining difference is the wdk-sys IddCx binding itself, invisible to
inspection. This commit keeps the upstream-matching structure (device context, no
interface) + the on-glass instrumentation; vendored wdk-build reverted to pristine.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packaging/windows/drivers/pf-vdisplay/build.rs

@@ -4,6 +4,12 @@
 fn main() -> Result<(), wdk_build::ConfigError> {
     wdk_build::configure_wdk_binary_build()?;
     link_iddcx_stub();
+    // wdk-build emits `/OPT:REF,ICF`. ICF (Identical COMDAT Folding) merges functions with identical
+    // bodies into ONE address — our many identical stub IddCx callbacks (`return STATUS_SUCCESS`) collapse
+    // to the same pointer (and even CRT EH handlers fold, hence the dumpbin `__CxxFrameHandler4 = DllMain`
+    // alias). The working virtual-display-rs links with NO `/OPT`, and IddCxAdapterInitAsync rejects a
+    // config whose distinct callbacks alias each other. Disable ICF (REF stays on); last `/OPT` wins.
+    println!("cargo::rustc-cdylib-link-arg=/OPT:NOICF");
     Ok(())
 }