[OE-core] Adding TARGET_VECTOR

[Kumar Gala]

We have some packages like flac that are aware of vectorization that may or may not exist on a given processor.  I was wondering if adding something like TARGET_VECTOR similar to TARGET_FPU made sense as a way for recipes to decide on how to set various vectorization flags if needed.

I was looking at this mostly from the PPC side in which we have:

TARGET_VECTOR = "" /* processor has no vector hw */
TARGET_VECTOR = "altivec" /* processor has AltiVec support */
TARGET_VECTOR = "spe" /* processor has signal processing engine support */
TARGET_VECTOR = "vsx" /* processor has Vector-Scalar Extension */

Not sure what makes sense for x86, ARM, or MIPS.

- k