Fixes unwinds from within a consolidation callback on ARM64EC, as the context frame could be x64 with UNWOUND_TO_CALL set, in which case LR contains garbage.
See: https://github.com/dotnet/runtime/blob/71abc26cf8f14f5d15665d7f580365ddfa296...
-- v2: ntdll: Don't restore PC from LR after unwinding through frame switches.