Fix `-Wmissing-variable-declarations` issue with `known_rights` global
Fix `-Wmissing-variable-declarations` issue with `known_rights` global

Staticize it since it is only used in the file.

Signed-off-by: Enji Cooper <d6bb01297bdcc8d1a5e14be12c1049fd9e385b00@gmail.com>

google/capsicum-test,google/capsicum-test,google/capsicum-test,google/capsicum-test