Move pbc subsystem to src/packfile

[whiteknight]

Following conventions of other subsystems, we should move all the packfile-related files into the src/packfile directory. This includes

src/packfile.c
src/packout.c
src/packdump.c

It may also include src/pmc_freeze.c, depending on how we want to classify that file (part of the packfile system or the pmc system).

As part of this work, we should move all subsystem-private function, macro, and structure definitions to src/packfile/packfile_private.h, and move all subsystem API functions into src/packfile/api.c

[bacek]

Hello.

-1 from me. +1 to implement Packfile PMCs properly (from both compile and runtime point of view)

-- Bacek

[whiteknight]

These files have already been moved to a new folder for now. We can still implement PMCs for this system, but for now the code we have is a little bit more organized.