Move System.Runtime.CompilerServices.CallConv* types to System.Private.CoreLib and expose via System.Runtime.#38473

Merged

jkotas merged 2 commits intodotnet:masterfrom jkoritzinsky:lower-callconv-types

Jun 27, 2020

+55-35

Commits on Jun 26, 2020

Move the calling convention types used in the new calling convention modopt-based encoding down to System.Private.CoreLib/System.Runtime.
jkoritzinsky
committed
Make S.R.CS.VisualC a partial facade so the tooling will generate the type forwards in the src assembly.
jkoritzinsky
committed