net/mosh broken after devel/abseil update

[Marc Baudoin <babafou%babafou.eu.org@localhost>]

Hi,

FYI, net/mosh build is broken after today's devel/abseil update:

[during configure]
/usr/pkgsrc/net/mosh/work/.buildlink/include/absl/base/policy_checks.h:81:2: error: #error "C++ versions less than C++17 are not supported."
   81 | #error "C++ versions less than C++17 are not supported."
      |  ^~~~~

and then more than 7000 lines of C++ whinings...