[hist7draw] improve I/O test for RCanvas with shared hist pointer
[hist7draw] improve I/O test for RCanvas with shared hist pointer

Exclude old workarounds, no need for TApplication
root-mirror/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,karies/root,karies/root,karies/root,root-mirror/root,root-mirror/root,olifre/root,root-mirror/root,karies/root,root-mirror/root,olifre/root,olifre/root,karies/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,karies/root,karies/root,olifre/root,karies/root,karies/root,karies/root,karies/root