Switch the build process to using Rust's new build system called
rustbuild. At the same time stop using jemalloc on all platforms and
switch to the system allocator since that was simplier to do.
Technically these dependencies change between versions. It just happens
that these two versions didn't change the dependencies but future
versions will so preemptively make the adjustment.
The path to the rust source changes from 1.15 so preemptively make
changes to prepare for that.
Signed-off-by: Derek Straka <derek@asterius.io>
Signed-off-by: Doug Goldstein <cardoe@cardoe.com>
Doug Goldstein
Johan Anderholm
Derek Straka