Fix for ccn-lite Kernel version to run on Linux Kernels > 4.15

Fixes all includes that were not working anymore when compiling for the Linux kernel since the restructuring of the ccn-lite project. Involved are all Files concerning the Linux Kernel Version.
With Linux Kernel headers > 4.15 the kernel timer changed, this uses the new way to do it. Solution adapted from here: https://gist.github.com/fcomida/081891670a11f90a5e44b166ec7479cb. Involved is ccnl-os-time.h and ccnl-os-time-c
Moves the definition of ccnl_malloc, ccnl_calloc and ccnl_free for the kernel version before on top of the includes of source files since the definitions are needed in them. Removes a superfluous definition of these functions from ccnl-malloc.h. Affected are ccnl-malloc.h and ccn-lite-lnxkernel.c
ccn-lite Linux Kernel Version now runs on Ubuntu 18.04 with kernel version 5.4

Fixes #300

cn-uofbasel / ccn-lite