rootd: do not use popen() to expand path names (#513)
rootd: do not use popen() to expand path names (#513)

Addressed security threat reported by S. Luders.
Using the same technology used in TSystem::ExpandFileName (with clang-format processing).
BerserkerTroll/root,simonpf/root,olifre/root,olifre/root,zzxuanyuan/root,BerserkerTroll/root,karies/root,davidlt/root,davidlt/root,karies/root,simonpf/root,davidlt/root,bbockelm/root,bbockelm/root,olifre/root,simonpf/root,karies/root,olifre/root,mhuwiler/rootauto,mhuwiler/rootauto,root-mirror/root,olifre/root,olifre/root,mhuwiler/rootauto,mhuwiler/rootauto,root-mirror/root,davidlt/root,agarciamontoro/root,root-mirror/root,davidlt/root,karies/root,davidlt/root,bbockelm/root,davidlt/root,zzxuanyuan/root,simonpf/root,simonpf/root,root-mirror/root,agarciamontoro/root,root-mirror/root,BerserkerTroll/root,mhuwiler/rootauto,olifre/root,agarciamontoro/root,bbockelm/root,root-mirror/root,davidlt/root,bbockelm/root,root-mirror/root,zzxuanyuan/root,bbockelm/root,agarciamontoro/root,karies/root,zzxuanyuan/root,davidlt/root,root-mirror/root,zzxuanyuan/root,simonpf/root,karies/root,bbockelm/root,davidlt/root,BerserkerTroll/root,agarciamontoro/root,simonpf/root,simonpf/root,agarciamontoro/root,agarciamontoro/root,bbockelm/root,root-mirror/root,karies/root,olifre/root,BerserkerTroll/root,zzxuanyuan/root,zzxuanyuan/root,karies/root,zzxuanyuan/root,bbockelm/root,zzxuanyuan/root,simonpf/root,mhuwiler/rootauto,mhuwiler/rootauto,agarciamontoro/root,davidlt/root,mhuwiler/rootauto,karies/root,simonpf/root,bbockelm/root,mhuwiler/rootauto,BerserkerTroll/root,simonpf/root,zzxuanyuan/root,agarciamontoro/root,root-mirror/root,root-mirror/root,BerserkerTroll/root,olifre/root,agarciamontoro/root,BerserkerTroll/root,karies/root,agarciamontoro/root,BerserkerTroll/root,mhuwiler/rootauto,olifre/root,olifre/root,bbockelm/root,zzxuanyuan/root,zzxuanyuan/root,mhuwiler/rootauto,BerserkerTroll/root,BerserkerTroll/root,karies/root