arch/sparc: add absic support

Add support for building SPARC targeted toolchain.
With this patch I have built a working sparc V8 (32 toolchain).

Testing shows that not all gcc versions works well:
4.4.1 OK (kernel builds and the final kernel can boot)
4.4.2 Not tested
4.4.3 Not tested
4.4.4 BAD (Kernel can build but fails during boot)
4.4.5 BAD (Kernel can build but fails during boot)
4.5.1 BAD (Build fails with a spill related ICE - http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35664)
4.5.2 OK (kernel builds and boots)

I have successfully been using the 4.5.2 version for a few months.

This patch does not add support for the LEON variant.
That may come later.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
[yann.morin.1998@anciens.enib.fr: for 32-bit, default CT_TARGET_ARCH is OK]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # powerpc specific configuration file

 config ARCH_POWERPC_SPE

     bool

     prompt "Enable SPE support"

     default n

     help

       Add support for the Signal Processing Engine.  This will set up

       the toolchain so that it supports the SPE ABI extensions. This

       mainly targets Freescale e500 processors.

       Setting this option will append "spe" to the end of your target

       tuple name (e.g., powerpc-e500v2-linux-gnuspe) so that the gcc

       configure/build system will know to include SPE ABI support.

       It will also automatically add "-mabi=spe -mspe" to your

       TARGET_CFLAGS, and "--enable-e500_double" to your CC_EXTRA_CONFIG,

       so you do not need to explicitly add them.