[Cmake] Custom Commands

[Brad King]

Kevin,

> What I'm doing is:
> 
> ADD_CUSTOM_TARGET -> creates gensrc.cxx
> SET_SOURCE_FILE_PROPERTIES(gensrc.cxx GENERATED)
> SOURCE_FILES( FILES ... gensrc)
> ADD_LIBRARY(libname FILES)

Try modifying your SOURCE_FILES command to refer to the file as
"gensrc.cxx" instead of "gensrc".  I'm pretty sure this stuff works if
used correctly, because I just used it recently in a small dummy project.

-Brad