the vanilla FindBoost.cmake pulled from cmake has couple assumptions
which do not hold in our environment. so address them case by case.
Signed-off-by: Kefu Chai <kchai@redhat.com>
CMake CMP0093 was introduced by CMake 3.15, but we only require CMake
v3.10.2. so use the old `Boost_VERSION_MACRO` variable by default,
unless specified otherwise.
Signed-off-by: Kefu Chai <kchai@redhat.com>
CMake CMP0074 was introduced by CMake 3.12, but we only require CMake
v3.10.2. so default to check `Boost_ROOT` unless specified otherwise.
Signed-off-by: Kefu Chai <kchai@redhat.com>
the FindBoost.cmake shipped by cmake 3.5.1 is not new enough to identify
the dependencies of boost 1.63 and up. so we need to copy the
FindBoost.cmake from cmake upstream. it supports up to boost 1.68.
Signed-off-by: Kefu Chai <kchai@redhat.com>
