Makefile could use 'chmod' on programs subdirectory

[Stephen Dowdy]

Makefile line:
cp -r programs '$(DESTDIR)$(PREFIX)/share/xdg-ninja/'
doesn't account for umask of running user, whereas all the 'install' directives explicitly set the modes.

I use a umask of 077 for 'root', thus the programs are not readable by group/other, requiring a postinstall:

sudo chmod 755 /opt/share/xdg-ninja/programs/
sudo chmod 644 /opt/share/xdg-ninja/programs/*

Thanks,
--stephen