[CMake] uname -p -> unknown

[Mathieu Malaterre]

Hi

according to the doc of uname:

...
   -p, --processor
              print the processor type or "unknown"
...

Well this is happening in my case:

$ uname -a
Linux arrakis 2.6.18-4-amd64 #1 SMP Fri May 4 00:37:33 UTC 2007 x86_64 GNU/Linux
$ uname -p
unknown
$ uname -m
x86_64


I do not know how important CMAKE_SYSTEM_PROCESSOR is, but could we
switch to 'uname -m' when 'uname -p' returns 'unknown'.

Thanks,
-- 
Mathieu