Raw syscall numbers were not platform independent, so replace them
with the helpers provided from the syscall.ph perl bits helper.
This makes reading the code easier as a nice side effect.
As syscall.ph is not an ordinary module and makes problems when it is
required by multiple modules we make a own module PVE::Syscall which
loads it and allows to export the necessary constants in a sane way.
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
