Fix reorder warnings (dotnet/core-setup#5821)

Fix reorder warnings (dotnet/core-setup#5821)

Add compiler flags to fail any builds that produce that warning.

The member initialization list is always evaluated in the order the
members are delcared in the class, not the order in which they are
listed in the member initialization list. So modify the member
initialization lists to match the order in which they will be evaluated.

Commit migrated from https://github.com/dotnet/core-setup/commit/dcbb048073e3745df48e52d0619648f7aae8fa3d