mailmap: add older email addresses for Kees Cook

This adds explicit mailmap entries for my older/other email addresses.
Reported-by: NJoe Perches <joe@perches.com>
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Link: https://lkml.kernel.org/r/20200910193939.3798377-1-keescook@chromium.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

.mailmap

@@ -169,6 +169,10 @@ Juha Yrjola <juha.yrjola@solidboot.com>
 Julien Thierry <julien.thierry.kdev@gmail.com> <julien.thierry@arm.com>
 Kamil Konieczny <k.konieczny@samsung.com> <k.konieczny@partner.samsung.com>
 Kay Sievers <kay.sievers@vrfy.org>
+Kees Cook <keescook@chromium.org> <kees.cook@canonical.com>
+Kees Cook <keescook@chromium.org> <keescook@google.com>
+Kees Cook <keescook@chromium.org> <kees@outflux.net>
+Kees Cook <keescook@chromium.org> <kees@ubuntu.com>
 Kenneth W Chen <kenneth.w.chen@intel.com>
 Konstantin Khlebnikov <koct9i@gmail.com> <khlebnikov@yandex-team.ru>
 Konstantin Khlebnikov <koct9i@gmail.com> <k.khlebnikov@samsung.com>