Protect TEnv::GetValue in case the DTORs of `TSystem' and `TUnixSystem' is called before `__do_global_dtors_aux' (thanks Christian Holm Christensen)
Protect TEnv::GetValue in case the DTORs of `TSystem' and `TUnixSystem' is called
before `__do_global_dtors_aux' (thanks Christian Holm Christensen)


git-svn-id: ecbadac9c76e8cf640a0bca86f6bd796c98521e3@5146 27541ba8-7e3a-0410-8455-c3a389f83636

dawehner/root,bbannier/ROOT,dawehner/root,bbannier/ROOT,dawehner/root,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,dawehner/root,dawehner/root,bbannier/ROOT,bbannier/ROOT,dawehner/root,dawehner/root,dawehner/root