title: cmake add_library at a custom location
body: <p>I need to build a library that is to be placed at a custom location stored in the variable CUSTOM_OUTDIR. Currently, I am using the following code to make sure that the library is copied to its proper location. </p>
  
  <pre><code>ADD_LIBRARY(example MODULE example.c)
  
  GET_TARGET_PROPERTY(FILEPATH example LOCATION)
  ADD_CUSTOM_COMMAND(
      TARGET example POST_BUILD 
      COMMAND ${CMAKE_COMMAND} 
      ARGS -E copy ${FILEPATH} ${CUSTOM_OUTDIR}
  )
  </code></pre>
  
  <p>However, this is not a good solution as the copying is done post_build, and I end up with two copies of the library. Is there a way to setup CMAKE_BINARY_DIR just for the <code>example</code> library so that only one copy of it is kept in the proper location?</p>