[CMake] CPACK_STRIP_FILES not working for files not built by project

[Ian Monroe]

My project is currently producing 100mb RPM/Deb's, but with stripped
binaries it should clock in at about 20mb.

I have CPACK_STRIP_FILES set to true.

Notably when I do make install/strip that doesn't seem to work either.
Looking more closely, I see that install/strip does work for the files
built by the project, but not some of the external libraries I'm
installing as well (so that they get picked up by CPack.)

Any suggestions? Adding strip manually is doable, just a bit
troublesome since I can't do cmake configuration time stuff like
file(glob.

Thanks,
Ian Monroe