[x86/Linux] Enable gcMarkFilterVarsPinned (WIN64EXCEPTIONS) (dotnet/coreclr#11281)

[x86/Linux] Enable gcMarkFilterVarsPinned (WIN64EXCEPTIONS) (dotnet/coreclr#11281)

* [x86/Linux] Enable gcMarkFilterVarsPinned

Do gcMarkFilterVarsPinned() for WIN64EXCEPTIONS

* [x86/Linux] GCInfo : Force this pointer untracked

`this` pointer is now always untracked so we can use pinned flag in tracked lifetimes.
This allows us to make the refs(inside filter) pinned to prevent from double-relocation.

* [x86/Linux] GCInfo : fix comment and formatting

* [x86/Linux] GCInfo : Update

- Force "this" pointer untracked only when "this" is generic context
- Style fixes

* [x86/Linux] GCInfo : remove this_OFFSET_FLAG

Commit migrated from https://github.com/dotnet/coreclr/commit/0c96db33ddb7d784cda9bd0368756046f436e8bc