- The name 'ninja' is used for several context.
At least, the name of executables in ${PREFIX}/bin/ninja
should be negogiated with others.

- PKGREVISION with date may be (should be) eliminated,
the tag 'release' claims the version 1.5.1.git.

- This is required at least by (OpenBSD) comms/rtl-sdr, just FYI
