[CMake] cmake hp-ux binary creates .sl libraries rather than .so libraries.

[Denis Scherbakov]

> Usually uname can report this, uname -m here on Linux.

The machine I am working on gives ia64.

PA-RISC machines give something strange: http://curl.haxx.se/mail/curlpp-2008-11/att-0051/config.log
 
> You are building HP-UX binaries on a Linux machine ?
> This would be really cross compiling.

Yes, it is.