Local install vs install for CPack generator

If we rerun cmake after make install in our project, we get CMake warnings

Cannot generate a safe runtime search path for target ... because
  files in some directories may conflict with libraries in implicit

    runtime library [libtiff.so.6] in /usr/lib/x86_64-linux-gnu may be hidden by files in:

  Some of these libraries may not be found correctly.

This is because make install copies installed libraries to another location (/usr/local/lib) that is also in our LD_LIBRARY_PATH [1].

The root cause for this is that we are confounding two different uses of the install command: For local installation, and for generating binary installers.

For local installation (compilation and installation on the same machine), we should install only our own artifacts, not third-party library dependencies that are already installed on our system.

For generating binary installers, however, we need to copy our own shared libraries and those we depend on to the same lib/ directory.

How to disentangle these two cases? Should we make the install statements conditional on a CMake option?

[1] CMake cannot resolve runtime directory path - Stack Overflow