On errors let make return with non-zero exitvalue
On errors let make return with non-zero exitvalue

This fixes https://github.com/gridcf/gct/issues/118
There are probably a few other places where we should bail out with a non-zero
exit value.

gridcf/gct,gridcf/gct,gridcf/gct,gridcf/gct,gridcf/gct,gridcf/gct