Error compiling catch on Ubuntu 21 gcc 11.2.0 about avcpp HOT 2 CLOSED

FAILED: rootdir/avcpp/tests/CMakeFiles/test_main.dir/test-main.cpp.o 
/usr/bin/c++  -I../rootdir/avcpp/catch2/single_include -fopenmp -g -std=gnu++17 -MD -MT rootdir/avcpp/tests/CMakeFiles/test_main.dir/test-main.cpp.o -MF rootdir/avcpp/tests/CMakeFiles/test_main.dir/test-main.cpp.o.d -o rootdir/avcpp/tests/CMakeFiles/test_main.dir/test-main.cpp.o -c ../rootdir/avcpp/tests/test-main.cpp
In file included from /usr/include/signal.h:328,
                 from ../rootdir/avcpp/catch2/single_include/catch2/catch.hpp:6323,
                 from ../rootdir/avcpp/tests/test-main.cpp:7:
../rootdir/avcpp/catch2/single_include/catch2/catch.hpp:9041:58: error: call to non-‘constexpr’ function ‘long int sysconf(int)’
 9041 |     constexpr static std::size_t sigStackSize = 32768 >= MINSIGSTKSZ ? 32768 : MINSIGSTKSZ;
      |                                                          ^~~~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/bits/sigstksz.h:24,
                 from /usr/include/signal.h:328,
                 from ../rootdir/avcpp/catch2/single_include/catch2/catch.hpp:6323,
                 from ../rootdir/avcpp/tests/test-main.cpp:7:
/usr/include/unistd.h:640:17: note: ‘long int sysconf(int)’ declared here
  640 | extern long int sysconf (int __name) __THROW;
      |                 ^~~~~~~
In file included from ../rootdir/avcpp/tests/test-main.cpp:7:
../rootdir/avcpp/catch2/single_include/catch2/catch.hpp:9100:45: error: size of array ‘altStackMem’ is not an integral constant-expression
 9100 |     char FatalConditionHandler::altStackMem[sigStackSize] = {};
      |                                             ^~~~~~~~~~~~