cmd/dist: use latest heap, sort packages for compiler bootstrap
The compiler depends on the way heap and sort break ties
in some cases. Instead of trying to find them all, bundle
those packages into the bootstrap compiler builds.
The overall goal is that Go1.4 building cmd/compile during the
bootstrap process produces a semantically equivalent compiler
to cmd/compile compiling itself. After this CL, that property is true,
at least for the compiler compiling itself and the other tools.