This commit removes the `compiler-rt` submodule from this repository.
The goal here is to align the `compiler-rt` used for compiling C
intrinsics with the upstream rust-lang/rust's usage of `llvm-project`.
Currently we have both an `llvm-project` repository as well as
`compiler-rt`, but they can naturally get out of sync and it's just one
more submodule to manage.
The thinking here is that the feature `c` for this crate, when
activated, will require the user to configure where the source code for
`compiler-rt` is present. This places the onus on the builder of
`compiler-builtins` to check-out and arrange for the appropriate
`compiler-rt` source code to be placed somewhere. For rust-lang/rust
this is already done with the `llvm-project` submodule, and we can
arrange for it to happen on this crate's CI anyway.
For users of this crate this is a bit of a bummer, but `c` is disabled
by default anyway and it seems unlikely that `c` is explicitly opted in
to all that much. (given the purpose of this crate)
This should allow us to archive the `compiler-rt` repository and simply
use `llvm-project` in the rust-lang/rust repository.
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).
