Remove linker repo '-h' patch adding reflection heuristics

[dagood]

There are a few ways like these that would make the patch go away:

• Merge the change into mono/linker.
• Create a dotnet/linker fork where the feature is maintained.

[crummel]

Might end up being taken by Linker after all; dotnet/linker#626.

[sbomer]

@dagood The patch should no longer be required with the latest linker updates. We're using sources straight from mono/linker now.

[MichaelSimons]

[Triage] Closing - All linker patches have been eliminated.