'make all' only builds stage 1

[brson]

It's not obvious from the makefile why this is

[nikomatsakis]

To expound: the target all should build rustc-H-${HOST_TRIPLE} which should build rustc-stage3-H-${HOST_TRIPLE} which ought to build stage3. But somehow this doesn't happen. Typing make rustc-stage3-H-x86_64-apple-darwin seems to work fine.

[brson]

make all actually works. it's just that make doesn't run make all