NetBSD ships with pkgsrc that installs versioned Python executables with suffix, like: python2.7 or python3.5.
CMake needs more help to detect appropriate name, so require where needed FindPythonInterp.
This diff addresses the following failure:
CMake Error at scripts/cmake_install.cmake:31 (file): file INSTALL cannot find "/tmp/pkgsrc-tmp/wip/lldb-git/work/build/lib/python.". Call Stack (most recent call first): cmake_install.cmake:37 (include) *** Error code 1