Fix a typo
core: Split combine.h and extract.h into two to reduce circular deps
Look for 64-bit #defines, not lack of them when determining arch
Add library-specific macros to detect the architecut
test: Check for __linux__ when determining availability of /proc/cpuinfo
altivec: Fix build
test: Work around MSVC not accepting alignment as a compile-time literal
math: Fix a bug in isnan()
shift: Inline neon::detail::shift_{r,l}

Optimization for zero shifts is handled in the frontend.
load: Fix unneccessary pessimization for NEON in load_splat(uint64<2>)
Fix unnecessary pessimizations on NULL arch
Redirect {permute,shuffle}_{z,}bytes16 to an existing impl in insn
Add ARMv8 A64 float64 support
memory: Use ARM64 A64 extended interleaving store/load intrinsics available
shuffle: Add support for table lookup insns available in ARMv8 A64
Move all compiler workarounds to single place