sync: update .mailmap

Update .mailmap based on bpftool's list of contributors and on the
latest .mailmap version in the upstream repository.

Signed-off-by: Quentin Monnet <qmo@kernel.org>

Author: qmonnet

.mailmap

@@ -1,6 +1,8 @@
 Changbin Du <changbin.du@intel.com> <changbin.du@gmail.com>
+Fangrui Song <i@maskray.me> <maskray@google.com>
 Geliang Tang <geliang@kernel.org> <geliang.tang@suse.com>
 Herbert Xu <herbert@gondor.apana.org.au>
+Jesper Dangaard Brouer <hawk@kernel.org> <brouer@redhat.com>
 Kees Cook <kees@kernel.org> <keescook@chromium.org>
 Maxim Mikityanskiy <maxtram95@gmail.com> <maximmi@nvidia.com>
 Quentin Monnet <qmo@kernel.org> <quentin@isovalent.com>