make: Don't print as many ==> and -- xxx -- lines in meta mode

[imp]

Summary

Since metamode just announces what it's doing, the extra -- xxx -- lines
aren't needed for recursive descent, nor are the ==> lines needed. This
speeds up rebuilding kernels a lot...

Sponsored by: Netflix

[imp]

A nice side effect of this is that it also shows us when we're bogusly rebuilding things more clearly too.

[sjg]

LGTM