This way, we can try to abstract uses of such calls between different compilers
that we support instead of repeating them in the headers due to differences in
compiler syntax/feature support.

Use the newly-added macros to abstract the one-liner intrinsic calls for
GCC/CLang and Visual Studio for building the SSE code, to reduce duplication.
It's not totally exhausive, but should cover quite a number of items.

Use the newly-added macros to abstract one-liner intrinsic calls for GCC/CLang
and Visual Studio for building the ARM NEON code, to reduce duplication.  It's
not totally exhausive, but should cover quite a number of items.

These macros can be used to abstract initializing SIMD data arrays for the
different compilers that we support, especially as we already require C99
support for building and using Graphene.

Use the macros that we just added to initialize the graphene_simd4f_t arrays
with the floats that we pass into graphene_simd4f_init*() as applicable.  This
especially simplifies the code for Visual Studio since we already require C99
support for building and using Graphene, and we can reduce some code
duplication.

We don't need identical typedefs separate for GCC/CLang and Visual Studio.  Put
them in one place for all cases.

We can define them instead to call the respective graphene_simd4f_get()
accordingly instead.

...with graphene_msvc_ instead of just _.  This attempts to make things clearer
to people.

...with graphene_msvc_ instead of just _.  This attempts to make things clearer
to people.