_Msh_clearAllTrapsIfFirstInSubshell(): tweak: just call 'die'
_Msh_clearAllTrapsIfFirstInSubshell(): tweak: just call 'die'

If we failed to unset all traps, we know we're in a subshell, so
no need to clean up before calling 'die', nor is the '|| return'
fallback needed: even on an interactive shell, the subshell will
be exited.

modernish/modernish