This is done to mitigate a build issue with lldb specific to CMake 3.4.*
This won't be a major issue on old distro (Debian jessie or Ubuntu Trusty) as CMake 3.4 isn't available on these distros.
CMake Error at tools/lldb/unittests/tools/lldb-mi/utils/CMakeLists.txt:12 (target_sources): Error evaluating generator expression: $<TARGET_OBJECTS:lldb-mi-utils> The evaluation of the TARGET_OBJECTS generator expression is only suitable for consumption by CMake. It is not suitable for writing out elsewhere.
Version 3.5 has been released 2016-04-15
While 3.4: 2016-01-25