clang.asan: unit tests fail

[mgondan]

to reproduce

cd swipl-devel
(change Ninja to "Unix\\ Makefiles" in scripts/configure script
mkdir build.clang.asan
cd build.clang.asan
../scripts/configure
make
ctest

The hello test with hello("世界", _Out) fails. I think it is the exception itself that fails:

% [3/256] cpp:hello ............................................................................................................. passed (0.001 sec)
% [4/256] cpp:hello ..AddressSanitizer: CHECK failed: asan_interceptors.cpp:463 "((__interception::real___cxa_throw)) != (0)" (0x0, 0x0) (tid=100242)
    #0 0x63ccdbb1efa5 in __asan::CheckUnwind() asan_rtl.cpp.o
    #1 0x63ccdbb39fe6 in __sanitizer::CheckFailed(char const*, int, char const*, unsigned long long, unsigned long long) (/home/matthias/swipl-devel/build.clang.asan/src/swipl+0xf6fe6) (BuildId: 922187003c1a2d84768253af0e47d9750e11344f)
    #2 0x63ccdbaf7e64 in __cxa_throw (/home/matthias/swipl-devel/build.clang.asan/src/swipl+0xb4e64) (BuildId: 922187003c1a2d84768253af0e47d9750e11344f)
    #3 0x7f2ab8bb948f in PlEx_fail(__PL_queryRef*) /home/matthias/swipl-devel/packages/cpp/SWI-cpp2.cpp:100:5
    #4 0x7f2ab8bb8e85 in PlTerm::get_nchars[abi:cxx11](unsigned int) const /home/matthias/swipl-devel/packages/cpp/SWI-cpp2.cpp:120:3
    #5 0x7f2ab8b8aa08 in PlTerm::as_string[abi:cxx11](PlEncoding) const /home/matthias/swipl-devel/packages/cpp/SWI-cpp2.h:634:12
    #6 0x7f2ab8b8aa08 in pl_hello__2(PlTermv) /home/matthias/swipl-devel/packages/cpp/test_cpp.cpp:110:28
    #7 0x7f2ab8b8aa08 in _pl_hello__2(unsigned long, int, __PL_foreign_context*) /home/matthias/swipl-devel/packages/cpp/test_cpp.cpp:105:1