Building tests fails with recent glibc

[krop]

with zug 0.1.0:

[  1%] Building CXX object test/__inline_var_tests/CMakeFiles/inline_var_tests.dir/main.cpp.o
In file included from /data/misc/zug-0.1.0/test/__inline_var_tests/main.cpp:2:
/data/misc/zug-0.1.0/tools/include/catch2/catch.hpp:10376:34: error: constexpr variable 'sigStackSize' must be initialized by a constant expression
    constexpr static std::size_t sigStackSize = 32768 >= MINSIGSTKSZ ? 32768 : MINSIGSTKSZ;
                                 ^              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/data/misc/zug-0.1.0/tools/include/catch2/catch.hpp:10376:58: note: non-constexpr function 'sysconf' cannot be used in a constant expression
    constexpr static std::size_t sigStackSize = 32768 >= MINSIGSTKSZ ? 32768 : MINSIGSTKSZ;
                                                         ^
/usr/include/bits/sigstksz.h:32:22: note: expanded from macro 'MINSIGSTKSZ'
# define MINSIGSTKSZ SIGSTKSZ
                     ^
/usr/include/bits/sigstksz.h:28:19: note: expanded from macro 'SIGSTKSZ'
# define SIGSTKSZ sysconf (_SC_SIGSTKSZ)
                  ^
/usr/include/unistd.h:640:17: note: declared here
extern long int sysconf (int __name) __THROW;
                ^
In file included from /data/misc/zug-0.1.0/test/__inline_var_tests/main.cpp:2:
/data/misc/zug-0.1.0/tools/include/catch2/catch.hpp:10435:33: error: variable length array declaration not allowed at file scope
    char FatalConditionHandler::altStackMem[sigStackSize] = {};
                                ^           ~~~~~~~~~~~~
2 errors generated

Also see: catchorg/Catch2#2421