Distutils forces strict floating point model on clang
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NumPy distutils will now always add the ``-ffp-exception-behavior=strict``
compiler flag when compiling with clang.  Clang defaults to a non-strict
version, which allows the compiler to generate code that does not set
floating point warnings/errors correctly.

Add release note about clang floating point error flag change
DOC: Add release note about clang floating point error flag change
