[llvm] [SampleProfile] Fix bug where intentionally constructed function with empty name asserts. (PR #71479)

[William Junda Huang via llvm-commits]

huangjd wrote:

Specifically in SampleProfileLoader::runOnFunction,


```
    if (auto RemppedName = Remapper->lookUpNameInProfile(CanonName)) {
          It = OutlineFunctionSamples.find(*RemppedName);
          if (It != OutlineFunctionSamples.end())
            Samples = &It->second;
        }
```
Triggers the assert because `*RemappedName` is empty. 


https://github.com/llvm/llvm-project/pull/71479