Bug 1560545 - Force-enable wayland support in Linux builds. r=chmanchester

So that we don't end up disabling it by accident.

Differential Revision: https://phabricator.services.mozilla.com/D35752

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

build/unix/mozconfig.linux

@@ -1,3 +1,12 @@
 . "$topsrcdir/build/unix/mozconfig.unix"
 
+case "$PERFHERDER_EXTRA_OPTIONS" in
+base-toolchains*)
+  # We don't build against wayland for base-toolchain builds.
+  ;;
+*)
+  ac_add_options --enable-default-toolkit=cairo-gtk3-wayland
+  ;;
+esac
+
 export MOZ_NO_PIE_COMPAT=1