Let Microsoft attributes apply to the type, not the variable.

Let Microsoft attributes apply to the type, not the variable.

There was already a function that moved attributes off the declspec into
an attribute list for attributes applying to the type, teach that function to
also move Microsoft attributes around and rename it to match its new broader
role.

Nothing uses Microsoft attributes yet, so no behavior change.

Part of https://reviews.llvm.org/D23895

llvm-svn: 280576