contrib: remove gitview

contrib: remove gitview

gitview did not have meaningful contributions since 2007, which gives the
impression it is either a mature or dead project.

In both cases we should not carry it in git.git as the README for contrib
states we only want to carry experimental things to give early exposure.

Recently a security vulnerability was reported by Javantea, so the decision
to either fix the issue or remove the code in question becomes a bit
more urgent.

Reported-by: Javantea <jvoss@altsci.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Acked-by: Aneesh Kumar K.V <aneesh.kumar@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>