Reset cleanup bit of TFileMerger in TBufferMerger::WriteOutput()
Reset cleanup bit of TFileMerger in TBufferMerger::WriteOutput()

In one of the stack traces of a crash in TBufferMerger it was noted that
there was an attempt to remove from a THashList the TFileMerger, even
though it is part of the stack of the thread it belongs to. Resetting
the cleanup bit of TFileMerger eliminates this problem.

agarciamontoro/root,root-mirror/root,mhuwiler/rootauto,bbockelm/root,mhuwiler/rootauto,agarciamontoro/root,mhuwiler/rootauto,simonpf/root,simonpf/root,BerserkerTroll/root,agarciamontoro/root,karies/root,simonpf/root,olifre/root,BerserkerTroll/root,karies/root,olifre/root,mhuwiler/rootauto,BerserkerTroll/root,karies/root,karies/root,bbockelm/root,BerserkerTroll/root,bbockelm/root,root-mirror/root,karies/root,mhuwiler/rootauto,zzxuanyuan/root,simonpf/root,root-mirror/root,simonpf/root,davidlt/root,olifre/root,bbockelm/root,mhuwiler/rootauto,agarciamontoro/root,bbockelm/root,agarciamontoro/root,karies/root,bbockelm/root,zzxuanyuan/root,karies/root,root-mirror/root,davidlt/root,root-mirror/root,zzxuanyuan/root,BerserkerTroll/root,agarciamontoro/root,bbockelm/root,bbockelm/root,simonpf/root,zzxuanyuan/root,zzxuanyuan/root,simonpf/root,mhuwiler/rootauto,zzxuanyuan/root,agarciamontoro/root,karies/root,simonpf/root,davidlt/root,zzxuanyuan/root,mhuwiler/rootauto,root-mirror/root,zzxuanyuan/root,agarciamontoro/root,davidlt/root,davidlt/root,mhuwiler/rootauto,mhuwiler/rootauto,agarciamontoro/root,olifre/root,root-mirror/root,olifre/root,karies/root,olifre/root,root-mirror/root,simonpf/root,davidlt/root,zzxuanyuan/root,bbockelm/root,davidlt/root,BerserkerTroll/root,BerserkerTroll/root,davidlt/root,olifre/root,karies/root,olifre/root,BerserkerTroll/root,root-mirror/root,olifre/root,simonpf/root,davidlt/root,simonpf/root,root-mirror/root,olifre/root,davidlt/root,olifre/root,zzxuanyuan/root,zzxuanyuan/root,BerserkerTroll/root,agarciamontoro/root,bbockelm/root,davidlt/root,root-mirror/root,mhuwiler/rootauto,karies/root,BerserkerTroll/root,agarciamontoro/root,bbockelm/root,zzxuanyuan/root,BerserkerTroll/root