Great rework and cleanups to ease PowerPC implementations definitions.

Great rework and cleanups to ease PowerPC implementations definitions.
* cleanup cpu.h, removing definitions used only in translate.c/translate_init.c
* add new flags to define instructions sets more precisely
* various changes in MMU models definitions
* add definitions for PowerPC 440/460 support (insns and SPRs).
* add definitions for PowerPC 401/403 and 620 input pins model
* Fix definitions for most PowerPC 401, 403, 405, 440, 601, 602, 603 and 7x0
* Preliminary support for PowerPC 74xx (aka G4) without altivec.
* Code provision for other PowerPC support (7x5, 970, ...).
* New SPR and PVR defined, from PowerPC 2.04 specification and other sources
* Misc code bugs, error messages and styles fixes.
* Update status files for PowerPC cores support.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3244 c046a42c-6fe2-441c-8c8c-71466251a162