Preserve qualifiers when getting fully qualified type

15f3cd6b moved the handling of UsingType
to a later point in the function getFullyQualifiedType.  This moved it
after the removal of an ElaboratedType and its qualifiers.  However,
the qualifiers were not added back, causing the fully qualified type to
have a qualifier mismatch with the original type.  Make sure the
qualifers are added before continuing to fully qualify the type.