https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98521

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94482

Clang incorrectly sets the alignment bit on 32-bit for the multiple load
instructions. This results in a bus error on hardware.

Similar to _mm_shuffle_epi8, qtbl/qtbx now split up to multiple shuffles on
A32V7. With multi-vector shuffles, two tables are created, the indexes
are subtracted, and either TBX'd on the result of the other table or ORR'd
together (TBX is mandatory for qtbx, but ORR is chosen when the lookups would
not be theoretically dual issued).

Caught by clang-14+

_make
_const
_extract_lane
_splat
_const_splat (also signed variants)

My attempt for the unsigned versions did not work

Fixes: #1008

https://learn.microsoft.com/en-us/cpp/intrinsics/x64-amd64-intrinsics-list?view=msvc-140

This intrinsic is the exception to the rule that MSVC x64 doesn't support intrinsics with MMX type arguments

Fixes: #1016

Another audit of the DIAGNOSTIC_PUSH / _PULL

as inspired by Emscripten

https://github.com/emscripten-core/emscripten/blob/dc94ff4cc1e9da5eb88672861be4f3eefb43c58f/system/include/compat/immintrin.h

Fixes: #967

Fixes: #929
Co-authored-by: Michael R. Crusoe <michael.crusoe@gmail.com>

Also cleanup some illegal double underscore variable names

Closes: #910