Pass reference to fstat() in RetryAfterSignal()
Pass reference to fstat() in RetryAfterSignal()

Without this patch llvm fails to compile due to a mismatch in argument
types since RetryAfterSignal() expects a reference to the callable.

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