ci: move libc mirrors to the rust-lang-ci-mirrors bucket

Author: pietroalbini

src/ci/docker/dist-various-1/install-mipsel-musl.sh

@@ -5,7 +5,7 @@ mkdir /usr/local/mipsel-linux-musl
 # Note that this originally came from:
 # https://downloads.openwrt.org/snapshots/trunk/malta/generic/
 # OpenWrt-Toolchain-malta-le_gcc-5.3.0_musl-1.1.15.Linux-x86_64.tar.bz2
-URL="https://rust-lang-ci2.s3.amazonaws.com/libc"
+URL="https://rust-lang-ci-mirrors.s3-us-west-1.amazonaws.com/rustc"
 FILE="OpenWrt-Toolchain-malta-le_gcc-5.3.0_musl-1.1.15.Linux-x86_64.tar.bz2"
 curl -L "$URL/$FILE" | tar xjf - -C /usr/local/mipsel-linux-musl --strip-components=2