devel/boost-*: update to 1.68.0

[jbeich]

Summary

Release announcement and calendar

Test Plan

• poudriere bulk -t devel/boost-all is green on 10.4 i386/amd64, 11.1 i386/amd64/armv6/aarch64, 12.0 i386/amd64/armv6/armv7/aarch64
• consumers will be tested via bug 229569

[jbeich]

• Bump TIMESTAMP in distinfo

[jbeich]

• Update to Beta 1 RC 2

[jbeich]

Switch to C++14 as Boost.System may fail without -DBOOST_NO_CXX14_CONSTEXPR otherwise. Affects at least:

• databases/clickhouse
• databases/mongodb34
• databases/mongodb36
• editors/jucipp
• math/cadabra2
• multimedia/mkvtoolnix
• science/libgeodecomp
• sysutils/osquery
• www/osrm-backend

[jbeich]

• Beta 1 is finally released

[jbeich]

• Include bug 229661 fix

[jbeich]

Oops, restore boost update after the last change.

[jbeich]

• Cherry-pick Boost.Optional fix to help unbreak games/freeorion

[jbeich]

• Switch to upstream CMake fix

[jbeich]

• Cherry-pick Boost.Rational fix to help unbreak net-p2p/qtum

[jbeich]

• Rebase after rP474979

[jbeich]

• Cherry-pick Boost.GIL fix to help unbreak games/freeorion

[jbeich]

• Cherry-pick Boost.GIL fix to help unbreak games/freeorion (2nd try)

[jbeich]

• Rebase after rP475584
• Update to RC1

[jbeich]

Oops, forgot about devel/boost-libs/pkg-plist:

====> Checking for pkg-plist issues (check-plist)
===> Parsing plist
===> Checking for items in STAGEDIR missing from pkg-plist
Error: Orphaned: include/boost/beast/core/detail/chacha.hpp
Error: Orphaned: include/boost/core/exchange.hpp
Error: Orphaned: include/boost/geometry/util/is_inverse_spheroidal_coordinates.hpp
===> Checking for items in pkg-plist which are not in STAGEDIR
Error: Missing: include/boost/fusion/view/transform_view/detail/apply_transform_result.hpp
===> Error: Plist issues found.
*** Error code 1

[jbeich]

• Fix libc++ >= 7 after USE_CXXSTD=gnu++14

[jbeich]

• Update to Release

[jbeich]

Landed in rP476723.