[llvm] [GSYM] Add support for querying merged functions in llvm-gsymutil (PR #120991)

[Greg Clayton via llvm-commits]

https://github.com/clayborg approved this pull request.

Just move `MergedFunctionsInfo::getFuncsDataExtractors` to after the decode function and this is good to go.

https://github.com/llvm/llvm-project/pull/120991