Small cleanup for HepMC for 4.0.1
Small cleanup for HepMC for 4.0.1:
- some header rearangement.
- Make sure HAVE_LIBZ is used to guard headers
- Drop "compressedAscii"
Would be nice to have it to have a look if one can have at least support for master HepMC3 before 4.1.0.
Edited by Andrii Verbytskyi