[clang] [HIP] Replace use of `llvm-mc` with `clang` (PR #112041)

[Matt Arsenault via cfe-commits]

================
@@ -463,10 +463,11 @@ void HIP::constructGenerateObjFileFromHIPFatBinary(
 
   Objf << ObjBuffer;
 
-  ArgStringList McArgs{"-triple", Args.MakeArgString(HostTriple.normalize()),
+  ArgStringList McArgs{"-target", Args.MakeArgString(HostTriple.normalize()),
                        "-o",      Output.getFilename(),
-                       McinFile,  "--filetype=obj"};
-  const char *Mc = Args.MakeArgString(TC.GetProgramPath("llvm-mc"));
+                       "-x",      "assembler",
+                       ObjinFile, "-c"};
+  const char *Mc = Args.MakeArgString(TC.GetProgramPath("clang"));
----------------
arsenm wrote:

But the toolchain tracked the name of the current clang? Really you want to find the current binary

`I don't think it's critical that the clang we invoke here is the amdclang`

It's critical to find the exact clang that you are running 

https://github.com/llvm/llvm-project/pull/112041