Avoid passing any constants or traced pointers to avoid
  compiler optimizations, so we make the sure the required
  instructions have been tested against the linker.

We would like to extend CPU feature detection infrastructure
for IBM Z CPU features. Eventually It will help to add and
enable Z specific SIMD builtins and instructions.
As part of the PR, we have extended ccompiler_opt.py,
npy_cpu_features.c.src, npy_cpu_features.h, other files for
Z CPU feature detection and added test files for VX/VXE/VXE2
in distutils/checks.

Updated `vfmlal_low_u32` and `vfmlslq_high_u32` to their `f16` new names.  Described here:

https://www.mail-archive.com/gcc-bugs@gcc.gnu.org/msg664008.html

Many of the intrinsics had names updated.  Supposedly previous specifications were not published so old names not required.

  Unlike GCC and CLANG, Intel Compiler exposes all supported intrinsics,
  whether or not the build options for those features are specified.
  Therefore, we must test #definitions of CPU features when option native/host
  is enabled via `--cpu-baseline` or through env var `CFLAGS` otherwise
  the test will be broken and leads to enable all possible features.

_builtin_popcount is always available, so the compile-time check always
succeeds.