[clang] [llvm] [HLSL][SPIRV][DXIL] Implement `dot4add_i8packed` intrinsic (PR #113623)

[Farzon Lotfi via cfe-commits]

================
@@ -934,6 +934,16 @@ uint64_t dot(uint64_t3, uint64_t3);
 _HLSL_BUILTIN_ALIAS(__builtin_hlsl_dot)
 uint64_t dot(uint64_t4, uint64_t4);
 
+//===----------------------------------------------------------------------===//
+// dot4add builtins
+//===----------------------------------------------------------------------===//
+
+/// \fn int dot4add_i8packed(uint A, uint B, int C)
+
+_HLSL_AVAILABILITY(shadermodel, 6.4)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_dot4add_i8packed)
+int dot4add_i8packed(unsigned int, unsigned int, int);
----------------
farzonl wrote:

is there a reason you didn't do `uint` here? Its the same, so just curious. 

https://github.com/llvm/llvm-project/pull/113623