ci: also build the build-manifest component on dist-x86_64-linux

Author: pietroalbini

src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile

@@ -98,7 +98,9 @@ ENV RUST_CONFIGURE_ARGS \
       --set llvm.thin-lto=true \
       --set llvm.ninja=false \
       --set rust.jemalloc
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS \
+        --include-default-paths \
+        src/tools/build-manifest
 ENV CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER=clang
 
 # This is the only builder which will create source tarballs