Packaging-related issues for .NET 5.0

[omajid]

I have started working on creating a .NET 5.0 package for Fedora based on source-build. I am using this issue to track all the individual issues. Some of them may also be tracked separately.

1. The just-built SDK contains no native/unmanaged debug information. Looks like all information has been stripped from the just-built SDK.

   runtime somehow lost the ability to keep debug info. It also lost flags to configure whether to keep debug info.

   For now, hacking around the strip_symbol and install_with_stripped_symbols in runtime/eng/native/functions.cmake things work: https://gist.github.com/omajid/3033f0d77c4e6d58fd2fffb0da685c12#file-runtime-dont-strip-patch

   A more correct/flexible fix needs to be merged into runtime.

2. Fedora's LDFLAGS break runtime build.

   I tried a quick hack (https://gist.github.com/omajid/3033f0d77c4e6d58fd2fffb0da685c12#file-cflags-patch) for Let builders provide customized CFLAGS for use by the runtime build  runtime#35727 and that seems to have fixed it 🤷

3. Private.SourceBuilt.Artifacts.*.tar.gz is missing.

[omajid]

cc @tmds @RheaAyase @aslicerh

[omajid]

Closing since each issue is now being tracked separately.

1. Tracked as Add an option to keep native debug symbols runtime#39203

2. Tracked as Support extra compiler flags during building runtime#39191

3. Tracked as Re-enable package-source-build in 5.0 for Private.SourceBuilt.Artifacts generation #1647