SCF222 says that dci_pdu in PDCCH PDU
(nfapi_nr_dl_tti_pdcch_pdu_rel15_t) should be an array, and not its
members.

Initially, filling the PDCCH and PDSCH nFAPI messages was split into a
separate function (in an attempt to keep the code structure similar to
LTE). However, this proved as not helpful: the nr_fill_nfapi_dl_pdu()
just filled the messages, with a parameter list almost size as long as
the actual messages (because most parameters are kind of independent).
This made no sense, so we put it back.

Also, from an understanding POV, they just fill a message as specified
in SCF222, so it should not be a problem.

- No dynamic allocation of PUCCH structures
- Use first PUCCH for HARQ (can only allocate for up to two slots in
  single PUCCH, simplistic nr_acknack_scheduling!)
- Use second PUCCH for CSI, do not multiplex!

CI: fix flexran-rtc build Xenial

See merge request oai/openairinterface5g!1007

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

MR991: Remove hack in LTE PDCP for noS1 mode  
- Removes a hack which was used when LTE PDCP was used for NR in noS1 mode

MR993: UL and DL fixes LDPC short codewords 
- Fix UL & DL LDPC decoding for short LDPC code, e.g. Z_c is not multiple of 8
- Fix DLSCH data transmission with multiple DMRS symbols per slot
- small TA fixes on OAI 5G NR UE
- Implemented CQI measurement at NR UE
- NR UE cleanup 

MR1000: doc: fix build directory in BASIC_SIM.md