First attempt at support for the Intel C/C++ compilers.
Still to-do:
- shared and module linker flags
- visibility support
- shutup lots of harmless, annoying remarks

To play with this:
- install Intel C/C++ compilers.
- set $PATH and $LD_LIBRARY_PATH correctly for the new stuff
- export CC=icc; export CXX=icpc
- mkdir kdelibs/build-icpc
- cd kdelibs/build-icpc
- cmake ..