[PATCH] Move non-dependent gdb::observers::observable::visit_state outside template

[Tom Tromey]

>>>>> "Pedro" == Pedro Alves <pedro@palves.net> writes:

Pedro> enum class visit_state is defined inside the class template
Pedro> observable, but it doesn't have to be, as it does not depend on the
Pedro> template parameters.  This commit moves it out, so that only one such
Pedro> type exists.  This reduces the size of a -O0 -g3 build for me by
Pedro> around 0.6%, like so:

Looks good to me.

Tom