test the mips64 targets
These should be all the required changes I think but libloading can't be cross compiled for these new targets:
```
error: failed to run custom build command for `libloading v0.3.1`
process didn't exit successfully: `/target/debug/build/libloading-07147fe7fffab0b2/build-script-build`(exit code: 101)
--- stderr
thread 'main' panicked at 'could not get target info: TargetNotFound', ../src/libcore/result.rs:799
note: Run with `RUST_BACKTRACE=1` for a backtrace.
```
I've openend nagisa/rust_libloading#19 to track that. Wel'll have to wait until that's fixed.
cc @alexcrichton
Update CI configs
* Run on the master branch (to get previews)
* Pass --target on AppVeyor (oops)
* Use the current nightly for arm (I think that bug is fixed)
notable changes in the docker-based testing infrastructure
- the docker containers can now modify $CARGO_HOME, to re-use the outer
Cargo registry, and the target directory to re-use build artifacts.
- the docker containers are removed when their execution finishes
because it's no longer necessary to re-start them to inspect them
because all the interesting output is in the outer target directory
This commit moves over most of the testing infrastructure to in-tree docker
images that are all dispatched to from Travis (no other test configuration).
This allows versioning modifications to the test infrastructure as well as the
code itself. Additionally separate docker images allows for easy modification of
one without worrying about tampering of others as well as easy addition of new
targets by simply adding a new `Dockerfile`.
Additionally this commit bundles the master version of the `compiler-rt` source
repository from `llvm-mirror/compiler-rt` to test against. The compiler-rt
library itself is compiled as a `cdylib` which is then dynamically located at
runtime and we look for symbols in. There's a few hoops here, but they currently
get the job done.
All tests now execute against both gcc_s and compiler-rt, and this
testing strategy is now all hidden behind a macro as well (refactoring
all existing tests along the way).
bors
Jorge Aparicio
Alex Crichton