Fix CMake install target
- copy lldb python module into directory specified with CMAKE_INSTALL_PREFIX
- make liblldb.so a symlink (to liblldb.so.X.Y where X.Y is the LLVM version)



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@182157 91177308-0d34-0410-b5e6-96231b3b80d8