support gcc-9.2.0 with c++17
P2_Support.hpp: operator() of predicate 'P2SpannedClip_Order' is made to be 'const'
fixed static_assert 'is_invocable_v<const _Compare&, const _Key&, const _Key&>'
Signed-off-by: Denis Pronin dannftk@yandex.ru
P2_Support.hpp: operator() of predicate 'P2SpannedClip_Order' is made to be 'const'
fixed static_assert 'is_invocable_v<const _Compare&, const _Key&, const _Key&>'
Signed-off-by: Denis Pronin dannftk@yandex.ru