In particular:
NotImplemented in llhttpnode.cpp
RelocateError in llupdateinstaller.cpp
LLProtectedDataException, LLCertException and subclasses in llsecapi.h

Had to add no-throw destructor overrides to LLCertException and subclasses
because otherwise clang complains that the implicitly-generated destructor's
exception specification is more lax than the base class's.