OpenBSD support in the tree has bitrotted since 3.2. This boils down to the following problems:

• OpenBSD ar lacks support for thin archives.
• LibreSSL is not caught by #if OPENSSL_VERSION_NUMBER ... preprocessor conditions.
• Missing header in stack_locator_openbsd.cpp.
• Missing ProcessInfo::getNumAvailableCores implementation.
• The Intel RDFPMathLib20U1 library defines fexcept_t in a way that conflicts with the OpenBSD libc.

Once these problems are fixed, and pending an open OpenBSD patch being merged to implement __cxa_thread_atexit, the following build command finishes successfully:

scons -j4 --ssl=SSL --use-system-pcre --use-system-yaml --use-system-zlib --use-system-icu --use-system-snappy CPPPATH=/usr/local/include LIBPATH=/usr/local/lib core tools