Cleanup: avoid referring to `std::vector<T>` members when `T` is incomplete.
This is [not legal](https://timsong-cpp.github.io/cppwp/n4868/vector#overview-4)
according to the C++ standard, and causes build errors in particular in C++20
mode. Fix it by defining the vector's type before using the vector.
Reviewed By: saugustine, MaskRay
Differential Revision: https://reviews.llvm.org/D135906
libtool uses file names to name members of an static library.
Files, located in different directories and having matching name,
would have the same name inside an archive. This is not a problem
for ld, but may be a problem for ar. This patch renames files
from ObjCopy library to avoid names clashing.
See https://reviews.llvm.org/D88827#3335814
Differential Revision: https://reviews.llvm.org/D120345
