[clang] [llvm] [HLSL][SPIR-V] Implement vk::push_constant (PR #166793)

[Nathan Gauër via cfe-commits]

================
@@ -3846,6 +3851,7 @@ static bool IsDefaultBufferConstantDecl(VarDecl *VD) {
          QT.getAddressSpace() == LangAS::Default &&
          VD->getStorageClass() != SC_Static &&
          !VD->hasAttr<HLSLVkConstantIdAttr>() &&
+         !VD->hasAttr<HLSLVkPushConstantAttr>() &&
----------------
Keenuts wrote:

Right, and I should also add a test targeting DXIL but using `vk::push_constant`

https://github.com/llvm/llvm-project/pull/166793