tests: avoid using cpp -dD
tests: avoid using cpp -dD

-dD is less portable across some peculiar preprocessors.

tests/Makefile.am (ksysent.h): Use cpp -dM instead of cpp -dD.

cuviper/strace,cuviper/strace,cuviper/strace,Saruta/strace,Saruta/strace,cuviper/strace,Saruta/strace,Saruta/strace,Saruta/strace,cuviper/strace