Bug 1525398 - temporarily disable the btup build. r=catlee

Differential Revision: https://phabricator.services.mozilla.com/D18737

--HG--
extra : moz-landing-system : lando

Author: Callek

taskcluster/ci/build/linux.yml

@@ -954,6 +954,7 @@ linux64-tup/opt:
         mozconfig-variant: tup
         tooltool-downloads: public
         need-xvfb: true
+    run-on-projects: []
     toolchains:
         - linux64-binutils
         - linux64-clang