Skip CI for aarch64-unknown-cloudabi for now

Author: JohnTitor

ci/build.sh

@@ -195,9 +195,10 @@ done
 
 # FIXME: https://github.com/rust-lang/rust/issues/58564
 # sparc-unknown-linux-gnu
+# FIXME: Today(2020-07-29)'s nightly is missing rust-src for this target.
+# aarch64-unknown-cloudabi
 RUST_LINUX_NO_CORE_TARGETS="\
 aarch64-pc-windows-msvc \
-aarch64-unknown-cloudabi \
 aarch64-unknown-freebsd \
 aarch64-unknown-hermit \
 aarch64-unknown-netbsd \