[llvm] [Offload] Cache symbols in program (PR #148209)

[Joseph Huber via llvm-commits]

https://github.com/jhuber6 commented:

Possible we could do the old
```
auto &Value = Map[Key];
if (!Value)
  Value = Start;
return Value;
```

https://github.com/llvm/llvm-project/pull/148209