this removes the last usage of the Platform plugin in NPL. It was being used for determining the
architecture of a running process locating the ELF file belonging to the process and parsing it.
Given that we are already attached to the process we can replace this with a more reliable method
using the "official" ptrace API for that (it doesn't look very official, but this is what e.g.
Together with a followup change, which I am in the process of preparing, this will shrink
lldb-server by 4%--9% (mostly depending on how large the file is right now -- i.e., if it
includes instruction emulator plugins).
Tested on x86 and arm.