glcpp: Use printf instead of "echo -n" in glcpp-test
I noticed that with /bin/sh on Mac OS X, "echo -n" does not work as desired, (it actually prints "-n" rather than suppressing the final newline). There is a /bin/echo that could be used (it actually works) instead of the builtin echo. But I decided it's more robust to just use printf rather than hardcoding /bin/echo into the script.