Check instead of relying on NOTREACHED
NOTREACHED was designed for traditional lint decades ago, and _Noreturn now normally subsumes its function. In the one case in Emacs where NORETURN might help and _Noreturn does not, check for NOTREACHED instead of assuming it. * lib-src/etags.c (main): * src/xterm.c (x_connection_closed): Remove NOTREACHED after a call to a _Noreturn function, as NOTREACHED is no longer needed there. Also, one of the NOTREACHEDs was misplaced, which defeated traditional lint checking anyway. * lib-src/pop.c (pop_getline): Redo so as to not need NOTREACHED. * src/emacs.c (main): Use eassume (false) rather than NOTREACHED, so that running with ENABLE_CHECKING catches any internal error causing the toplevel Frecursive_edit to return.