recvfrom() returns ssize_t, not size_t.

There was a problem in rrc_gNB_process_NGAP_PDUSESSION_RELEASE_COMMAND()
where we PROTOCOL_CTXT_SET_BY_INSTANCE() that does not initialize
eNB_index leading to a crash later on in pdcp. So let's initialize
everything.

Plus, while we're here, use do { } while(0) in the macros, just to avoid
problems like:

  if (condition)
    macro;

Without do { } while(0) only the first statement of the macro is done
in the if. (Not sure if the code has the problem somewhere, but doesn't
hurt to fix.)

There was a crash when we exit the nr softmodem with AW2S device.
The array rxbase[] was surely freed() by some other thread, so
let's not access it after detecting oai_exit != 0.

We also need to unblock a possible reader thread. The chosen way to
do may be not the best. To be checked.

integration_2023_w02

See merge request oai/openairinterface5g!1906

!1796 Make SFN dependent on GPS time
!1874 Processing time optimization for SRS
!1881 Fix documentation of dot_product()
!1884 Prevent Msg3 to be scheduled in downlink slot when nrofUplinkSymbols = 0 and DDDSU
!1888 Adopting new BWP structure at UE (first MR)
!1890 Fix setup_time overflow in VNF processing thread
!1892 system.c cleaning check result of system call
!1893 fix buildhelper Soapy folder name, case not respected, reinstall was broken
!1894 doc(ci): adding constraint on the branch name
!1895 ASN_SEQUENCE_ADD return code was checked only in 0.5% of calls
!1900 bugfix CU/DU: use correct IP address for GTP-U
!1901 Adding NRPPA ASN1 definitions and library
!1903 bugfix in function channelmod_modify_cmd
!1867 CI: new Python classes for SSH & Local execution
restore LDPC docs

Merge remote-tracking branch 'origin/FAPI_fix_setup_time_from_overflowing' into integration_2023_w02

Fix setup_time overflow in vnf processing thread, preventing gNB from stopping message processing once setup_time overflowed

- Mention python version and separate Python/own modules
- Use constants for registry and namespace name
- Provide OC url in oc login
- Do not perform oc logout in background