et @6.2.8_0: Undefined symbols for architecture x86_64 "std::bad_optional_access…"

[chrstphrchvz (Christopher Chavez)]

std::bad_optional_access is provided by libc++ only since macOS 10.13 High Sierra, so the macOS 10.7 - 10.12 builds fail to link:

Undefined symbols for architecture x86_64:
  "std::bad_optional_access::~bad_optional_access()", referenced from:
      __ZNSt3__127__throw_bad_optional_accessB7v160006Ev in libTerminalCommon.a(ServerFifoPath.cpp.o)
  "typeinfo for std::bad_optional_access", referenced from:
      __ZNSt3__127__throw_bad_optional_accessB7v160006Ev in libTerminalCommon.a(ServerFifoPath.cpp.o)
  "vtable for std::bad_optional_access", referenced from:
      __ZNSt3__127__throw_bad_optional_accessB7v160006Ev in libTerminalCommon.a(ServerFifoPath.cpp.o)
  NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64

Note: I personally do not use this port or these macOS versions.