Emacs warns that makefile lines that start with spaces followed by
tabs are "suspicious". These were harmless since they were
continuation lines, but getting rid of the warning is nice and this
version looks better.
The first commit fixes the "jobserver unavailable" warning reported at gentoo/gentoo-rust#29. I don't think the warning is related to the compilation failure shown there.
The remaining commits are minor fixes I noticed while investigating the jobserver warning.