FindBoost: Fix old context lib discovery
Old versions provide boost/context/all.hpp
and new versions provide boost/context/detail/fcontext.hpp
but nether is provided by all versions.
Fixes: #18126 (closed)
Topic-rename: FindBoost-old-context
Old versions provide boost/context/all.hpp
and new versions provide boost/context/detail/fcontext.hpp
but nether is provided by all versions.
Fixes: #18126 (closed)
Topic-rename: FindBoost-old-context