Address build error on Apple M1 from random-number headers

[edwenger]

In file included from /Users/ewenger/GitHub/emodlib/include/emodlib/utils/RANDOM.cpp:1:
In file included from /Users/ewenger/GitHub/emodlib/include/emodlib/utils/RANDOM.h:20:
In file included from /Library/Developer/CommandLineTools/usr/lib/clang/13.0.0/include/emmintrin.h:13:
In file included from /Library/Developer/CommandLineTools/usr/lib/clang/13.0.0/include/xmmintrin.h:13:
/Library/Developer/CommandLineTools/usr/lib/clang/13.0.0/include/mmintrin.h:33:5: error: use of undeclared identifier '__builtin_ia32_emms'; did you mean '__builtin_isless'?
    __builtin_ia32_emms();
    ^

Seems to be related to these:

• https://github.com/libigl/libigl/issues/1686
• https://stackoverflow.com/questions/65555170/unable-to-run-make-command-for-bwa-on-apple-m1-on-mac-os-big-sur

[edwenger]

This seems to be the trick: https://github.com/DLTcollab/sse2neon

Usage

• Put the file sse2neon.h in to your source code directory.

• Locate the following SSE header files included in the code:

  #include <xmmintrin.h>
  #include <emmintrin.h>

  {p,t,s,n,w}mmintrin.h should be replaceable, but the coverage of these extensions might be limited though.

• Replace them with:

  #include "sse2neon.h"

[edwenger]

See b37441215deba484aa745b7f7ec0c0f0835811f4

[edwenger]

Generalizing to either the Mac M1 or Linux case with pre-processor directives (as described here):

• https://stackoverflow.com/a/66256378
• https://stackoverflow.com/a/5920028

See commit https://github.com/edwenger/emodlib/commit/88d6d7eef13981c4f081fff730791e90f658787d