--enable-expensive-hardening has hard-to-debug failures when run-time libraries aren't installed

If libabsan or libubsan or libclang_rt.asan or libclang_rt.ubsan is missing, and you try to build with --enable-expensive-hardening, then the autoconf scripts will generate an orconfig.h file that doesn't allow Tor to compile.

What we should probably do here is warn about the missing libraries when --enable-expensive-hardening is in use but the runtime libraries are not present.