graphene-config: Hide SIMD implementation from GObject-Introspection
graphene-config: Hide SIMD implementation from GObject-Introspection

Exposing the various #mesondefine'd constants results in the GIR XML
unnecessarily varying between architectures.

Conversely, GObject-Introspection's rather simplistic cpp parser
thinks GRAPHENE_SIMD_S is always defined to "sse", even on
architectures where it should not be.

Introspected code is not going to be able to use SIMD anyway, so this
doesn't seem to have any value.

Resolves: https://github.com/ebassi/graphene/issues/211
Signed-off-by: Simon McVittie <0e1aea601907c1a85c2dc96e5ea37e23c58d2e9b@debian.org>

ebassi/graphene,ebassi/graphene