[Bug lto/106328] Build doesn't respect -j N flag

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106328

--- Comment #9 from Martin Liška <marxin at gcc dot gnu.org> ---
> Magically only with recent GNU make, otherwise needs proper prefixed
> rules in the lto-wrapper generated makefile which I don't think we do.

Wait, the cooperation works with older GNU make if a Makefile uses prefixed (+)
rules. WPA does not email any artificial Makefile for WPA streaming. It's a
Makefile we emit for LTRANS run, e.g.:

marxin@marxinbox:/dev/shm/objdir> cat /tmp/ccuhgkQs.mk
./a.ltrans0.ltrans.o:
        @g++  '-xlto' '-c' '-fno-openmp' '-fno-openacc' '-fno-pie'
'-fcf-protection=none' '-mtune=generic' '-march=x86-64' '-O2' '-save-temps'
'-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64' '-dumpdir' 'a.'
'-dumpbase' './a.ltrans0.ltrans' '-fltrans' '-o' './a.ltrans0.ltrans.o'
'./a.ltrans0.o'
./a.ltrans1.ltrans.o:
        @g++  '-xlto' '-c' '-fno-openmp' '-fno-openacc' '-fno-pie'
'-fcf-protection=none' '-mtune=generic' '-march=x86-64' '-O2' '-save-temps'
'-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64' '-dumpdir' 'a.'
'-dumpbase' './a.ltrans1.ltrans' '-fltrans' '-o' './a.ltrans1.ltrans.o'
'./a.ltrans1.o'
...

So what can be miss is jobserver detection on BSD that can fail for some
reason, but it should work fine apart from that. Or do I miss something?