Bug 1720483 - Port bug 1719229: Use sysroot for host build targets. r=justdave

Port of D119848.

Differential Revision: https://phabricator.services.mozilla.com/D119889

--HG--
extra : amend_source : d497d815fbf293fb4f3aa98e33e51ca0d21cc8f6

taskcluster/ci/build/linux.yml

@@ -314,6 +314,7 @@ linux/opt:
             - linux64-rust-size
             - linux64-sccache
             - sysroot-i686-linux-gnu
+            - sysroot-x86_64-linux-gnu
 
 linux-shippable/opt:
     description: "Linux32 Shippable"
@@ -362,6 +363,7 @@ linux-shippable/opt:
             - linux64-rust
             - linux64-rust-size
             - sysroot-i686-linux-gnu
+            - sysroot-x86_64-linux-gnu
 
 linux/debug:
     description: "Linux32 Debug"
@@ -404,3 +406,4 @@ linux/debug:
             - linux64-rust-size
             - linux64-sccache
             - sysroot-i686-linux-gnu
+            - sysroot-x86_64-linux-gnu