This was done so it would work when circular buffer holds other things
that are not unique_pointers. Queue and pop_func had to be made public
to be able to call the pop_func when an SDU is discarded.
* Added ability to discard to dyn_block_queue
* Change way of keeping track of SDUs
* Check nullptr in poping callback. Starting to check for nullptr in RLC read_pdu.
* Adding RLC discard tests
* Clearing PDCP info when RLC discard happens
* Read SDUs until they are no longer nullptr
* Changed discard_if to use template argument
we've seen a heap-buffer overflow in fmt because printf wasn't using
the right formtter for size_t, which should be %zu
this patch fixes it for the PDCP LTE entity but we might have it elsewhere too
[1m[31m==7595==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x629000e6f1fc at pc 0x562273a45289 bp 0x7f35567641f0 sp 0x7f35567641e0
[1m[0m[1m[34mREAD of size 4 at 0x629000e6f1fc thread T12 (STACK)[1m[0m
0 0x562273a45288 in fmt::v7::basic_format_arg<fmt::v7::basic_printf_context<std::back_insert_iterator<fmt::v7::detail::buffer<char> >, char> > fmt::v7::detail::make_arg<fmt::v7::basic_printf_context<std::back_insert_iterator<fmt::v7::detail::buffer<char> >, char>, unsigned int>(unsigned int const&) (/osmo-gsm-tester-srsue/srslte/bin/srsue+0x9dc288)
1 0x562273a3aa86 in void fmt::v7::dynamic_format_arg_store<fmt::v7::basic_printf_context<std::back_insert_iterator<fmt::v7::detail::buffer<char> >, char> >::emplace_arg<unsigned int>(unsigned int const&) (/osmo-gsm-tester-srsue/srslte/bin/srsue+0x9d1a86)
2 0x562273a308e7 in void fmt::v7::dynamic_format_arg_store<fmt::v7::basic_printf_context<std::back_insert_iterator<fmt::v7::detail::buffer<char> >, char> >::push_back<unsigned int>(unsigned int const&) /mnt/data/jenkins/workspace/srslte_ogt_trial_builder_x86-ubuntu1804-asan/srsLTE/lib/include/srslte/srslog/bundled/fmt/core.h:1548
3 0x562274361541 in void srslog::log_channel::operator()<unsigned int&, unsigned int&, unsigned long>(char const*, unsigned int&, unsigned int&, unsigned long&&) /mnt/data/jenkins/workspace/srslte_ogt_trial_builder_x86-ubuntu1804-asan/srsLTE/lib/include/srslte/srslog/log_channel.h:101
4 0x56227430d9e7 in srslte::pdcp_entity_lte::update_rx_counts_queue(unsigned int) /mnt/data/jenkins/workspace/srslte_ogt_trial_builder_x86-ubuntu1804-asan/srsLTE/lib/src/upper/pdcp_entity_lte.cc:451