[cxxmodules] Add dependencies to C++ modules generated by rootcling
[cxxmodules] Add dependencies to C++ modules generated by rootcling

Previously the modules were only a environment variable, so we never
had any CMake code that added the correct dependencies here. Now we
do have runtime_cxxmodules, and we can actually properly add a
dependency here.
Without this patch a deleted C++ module file actually will never be regenerated.

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