[cxxmodules] Add a missing bits header to the modulemap.
[cxxmodules] Add a missing bits header to the modulemap.

Should fix ROOT-10316 and ROOT-10317

olifre/root,olifre/root,karies/root,karies/root,olifre/root,karies/root,root-mirror/root,karies/root,olifre/root,root-mirror/root,karies/root,karies/root,root-mirror/root,root-mirror/root,root-mirror/root,karies/root,root-mirror/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,olifre/root,root-mirror/root,karies/root,root-mirror/root,karies/root,olifre/root,olifre/root,olifre/root,root-mirror/root,olifre/root,karies/root,olifre/root