Move CloudABI to tier 3.

src/ci/docker/host-x86_64/dist-various-2/Dockerfile

@@ -61,8 +61,6 @@ RUN env \
 
 WORKDIR /tmp
 COPY host-x86_64/dist-various-2/shared.sh /tmp/
-COPY host-x86_64/dist-various-2/build-cloudabi-toolchain.sh /tmp/
-RUN /tmp/build-cloudabi-toolchain.sh x86_64-unknown-cloudabi
 COPY host-x86_64/dist-various-2/build-fuchsia-toolchain.sh /tmp/
 RUN /tmp/build-fuchsia-toolchain.sh
 COPY host-x86_64/dist-various-2/build-solaris-toolchain.sh /tmp/
@@ -97,7 +95,6 @@ ENV TARGETS=$TARGETS,wasm32-wasi
 ENV TARGETS=$TARGETS,sparcv9-sun-solaris
 ENV TARGETS=$TARGETS,x86_64-sun-solaris
 ENV TARGETS=$TARGETS,x86_64-unknown-linux-gnux32
-ENV TARGETS=$TARGETS,x86_64-unknown-cloudabi
 ENV TARGETS=$TARGETS,x86_64-fortanix-unknown-sgx
 ENV TARGETS=$TARGETS,nvptx64-nvidia-cuda
 ENV TARGETS=$TARGETS,armv7-unknown-linux-gnueabi

src/doc/rustc/src/platform-support.md

@@ -128,7 +128,6 @@ target | std | host | notes
 `x86_64-linux-android` | ✓ |  | 64-bit x86 Android
 `x86_64-rumprun-netbsd` | ✓ |  | 64-bit NetBSD Rump Kernel
 `x86_64-sun-solaris` | ✓ |  | 64-bit Solaris 10/11, illumos
-`x86_64-unknown-cloudabi` | ✓ |  | 64-bit CloudABI
 `x86_64-unknown-freebsd` | ✓ | ✓ | 64-bit FreeBSD
 `x86_64-unknown-illumos` | ✓ | ✓ | illumos
 `x86_64-unknown-linux-gnux32` | ✓ |  | 64-bit Linux (x32 ABI) (kernel 4.15, glibc 2.27)
@@ -208,6 +207,7 @@ target | std | host | notes
 `x86_64-linux-kernel` | ? |  | Linux kernel modules
 `x86_64-pc-solaris` | ? |  |
 `x86_64-pc-windows-msvc` | ✓ |  | 64-bit Windows XP support
+`x86_64-unknown-cloudabi` | ✓ |  | 64-bit CloudABI
 `x86_64-unknown-dragonfly` | ✓ | ✓ | 64-bit DragonFlyBSD
 `x86_64-unknown-haiku` | ✓ | ✓ | 64-bit Haiku
 `x86_64-unknown-hermit` | ? |  |