exception.h: error: ISO C++17 does not allow dynamic exception specifications

[barracuda156]

Build fails on macOS for me. One problem is that libutil/threads/tls.h fails to recognize emulated TLS provided by GCC:

:info:build In file included from /opt/local/var/macports/build/_opt_PPCRosettaPorts_math_libtensor/libtensor/work/libtensor-0e82b4f07adf0eb1d6a617d93e9deb6f43d24ede/libtensor/core/impl/combined_orbits_impl.h:4,
:info:build                  from /opt/local/var/macports/build/_opt_PPCRosettaPorts_math_libtensor/libtensor/work/libtensor-0e82b4f07adf0eb1d6a617d93e9deb6f43d24ede/libtensor/core/impl/combined_orbits.C:2:
:info:build /opt/local/var/macports/build/_opt_PPCRosettaPorts_math_libtensor/libtensor/work/libtensor-0e82b4f07adf0eb1d6a617d93e9deb6f43d24ede/libutil/threads/tls.h:43:2: error: #error Please read https:
:info:build    43 | #error Please read https://download.q-chem.com/trac/wiki/CompileCcman
:info:build       |  ^~~~~

Then immediately several C++17 standard errors follow:

:info:build In file included from /opt/local/var/macports/build/_opt_PPCRosettaPorts_math_libtensor/libtensor/work/libtensor-0e82b4f07adf0eb1d6a617d93e9deb6f43d24ede/libtensor/exception.C:3:
:info:build /opt/local/var/macports/build/_opt_PPCRosettaPorts_math_libtensor/libtensor/work/libtensor-0e82b4f07adf0eb1d6a617d93e9deb6f43d24ede/libtensor/exception.h:278:5: error: ISO C++17 does not allow dynamic exception specifications
:info:build   278 |     throw(exception);
:info:build       |     ^~~~~

[barracuda156]

Dynamic exception specifications are in fact not supported in C++17: https://stackoverflow.com/questions/47284705/c1z-dynamic-exception-specification-error