https://llvm.org/docs/PDB/index.html

https://llvm.org/docs/CommandGuide/llvm-pdbutil.html

https://www.infoq.com/news/2017/08/LLVM-PDB
https://www.infoq.com/news/2017/02/Portable-PDB

https://github.com/Microsoft/microsoft-pdb
https://github.com/dotnet/symreader-portable
https://github.com/dotnet/corefx/blob/master/src/System.Reflection.Metadata/specs/PortablePdb-Metadata.md