[CMake] Check if variable is already is cache

[Marcel Loose]

Hi all,

I vaguely remember I read on this mailing list that it is possible to
check whether a variable is already in cache. Something like this:

if(CACHED var)
 ...
endif(CACHED var)

However, I cannot find anything about this in the manual.
Is it possible, or does my memory serve me bad?

Best regards,
Marcel Loose.