[CUDA][HIP] Fix hostness of defaulted constructor

Clang does not respect the explicit device host attributes of defaulted special members.
Also clang does not respect the hostness of special members determined by their
first declarations.
Clang also adds duplicate implicit device or host attributes in certain cases.
This patch fixes that.
Differential Revision: https://reviews.llvm.org/D67509

llvm-svn: 372394