Add missing <functional> header
Add missing <functional> header

We use std::function which is defined in <functional> header.

Signed-off-by: David Abdurachmanov <c087e48302f7476d5d88ea1a1a98ff646e8a8d3e@gmail.com>

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