[llvm] [DWARF] Speedup .gdb_index dumping (PR #151806)

[via llvm-commits]

itrofimow wrote:

> For argument's sake - could you check the performance with a binary search? See if it's acceptable for your use case. Be nice not to have to build another data structure.

With the hashtable user-time averages to `3.73`s
With the binary search user-time averages to `4.21`s

Both are perfectly fine for me, your call

https://github.com/llvm/llvm-project/pull/151806