[llvm] [SampleFDO] Support enabling sample loader pass in O0 mode (PR #113985)

[Matthias Braun via llvm-commits]

================
@@ -2326,6 +2327,9 @@ PreservedAnalyses SampleProfileLoaderPass::run(Module &M,
 
   if (!FS)
     FS = vfs::getRealFileSystem();
+  if (!DisableSampleLoaderInlining.getNumOccurrences() &&
+      DisableSampleProfileInlining)
+    DisableSampleLoaderInlining = true;
----------------
MatzeB wrote:

I think this mixes up global variable and class field and may be good to allow setting true and false from command line?
```suggestion
  if (!::DisableSampleLoaderInlining.getNumOccurrences())
    this->DisableSampleLoaderInlining = ::DisableSampleLoaderInlining;
```

https://github.com/llvm/llvm-project/pull/113985