[CMake] Figuring out dependencies for a library in order to build

[E. Wing]

> 
> If ${MY_OUTPUT} expands to nothing then you will have an invalid IF
> statement, to be safe quote the argument so that if it isn't set you will at
> least have IF ("" MATCHES "_MikMod_") which is valid
> 

Your suggestion about adding the quotes worked. But I think this is
weird because ${MY_OUTPUT} has always been filled with lots of output
data. I do a MESSAGE(${MY_OUTPUT}) right before the IF call, and I
always see a large body of text. So I don't really understand why it
was failing.

Thanks,
Eric