Rollup merge of rust-lang#64786 - tmandry:patch-1, r=Mark-Simulacrum

Use https for curl when building for linux

I noticed that the dist-x86_64-linux builder uses http to fetch curl and doesn't do any signature verification. It should probably use https.

r? @alexcrichton @Mark-Simulacrum

src/ci/docker/dist-x86_64-linux/build-curl.sh

@@ -5,7 +5,7 @@ source shared.sh
 
 VERSION=7.51.0
 
-curl http://cool.haxx.se/download/curl-$VERSION.tar.bz2 | tar xjf -
+curl https://cool.haxx.se/download/curl-$VERSION.tar.bz2 | tar xjf -
 
 mkdir curl-build
 cd curl-build