[CMake] OSX universal binary support

[Bill Hoffman]

Sean McBride wrote:
> On 1/15/08 9:59 AM, Mike Jackson said:
> 
> In addition to what other's said, I'll just add the following:
> 
>> Funny.. last time I asked I was told to use "i386 ppc" which did not  
>> work and so I started adding the flags myself. Using a ";" instead of  
>> a space does allow universal binaries to be produced.
> 
> CMake also supports building 4-way fat by specifying "i386;ppc;ppc64;x86_64".
> 
>> Of course one has to be careful when doing this with endian specific  
>> code. Have both PPC and i386 is basically cross compiling and trying  
>> to determine the proper byte ordering of the target machine is prone  
>> to errors. Just FYI for those with this type of code.
> 
> It is best to avoid any TRY_RUN if you want to build universal. 
> Instead, you can check endianness at compile time (the compiler knows
> the endianness of the machine its building for of course).  You can use
> #if __BIG_ENDIAN__ (something like that).
> 
I have added a FAQ for this here:

http://www.cmake.org/Wiki/CMake_FAQ#Platform-specific_questions

If anyone wants to add more feel free...

-Bill