INSTALL.cmake clarification

[Scott Kostyshak]

When is the following true?

    When you want to run LyX without installing from a out-of-source
    build directory you have to set the environment variable LYX_DIR_21x
    and it must point to the lib dir in the source tree.
        Linux/Unix: export LYX_DIR_21x=<lyx-source>/lib
        Windows   : set LYX_DIR_21x=<lyx-source>\lib

I have used out-of-source and in-source Cmake builds and have never
had to set the environment variable. Cmake doesn't take care of this
automatically?

Scott