Merge pull request #212 from VectorCamp/bugfix/fix-simde-build

SIMDe on Clang needs SIMDE_NO_CHECK_IMMEDIATE_CONSTANT defined and other SIMDe related fixes now that SIMDe is part of the CI pipeline.

Some issue with SIMDe on x86 still remains because of an upstream bug:

https://github.com/simd-everywhere/simde/issues/1119

Similarly SIMDe native with clang on Arm also poses a non-high priority build failure:

https://buildbot-ci.vectorcamp.gr/#/builders/129/builds/11

Possibly a SIMDe issue as well, need to investigate but will merge this PR as these are non-blockers.