[llvm-objcopy] Cleanup errors from CopyConfig and remove llvm-objcopy.h dependency

error() was previously cleaned up from CopyConfig, but new uses were introduced.

This also tweaks the error message for --add-symbol to report all invalid flags.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@356105 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed