https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109898
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
That seems to be new in Make 4.4, because the manual for Make 4.3 says:
'.NOTPARALLEL'
If '.NOTPARALLEL' is mentioned as a target, then this invocation of
'make' will be run serially, even if the '-j' option is given. Any
recursively invoked 'make' command will still run recipes in
parallel (unless its makefile also contains this target). Any
prerequisites on this target are ignored.
