This implements a set of vectorized math routines to be used by the
compiler auto-vectorizer. Versions for vectors with 2 lanes up to
64 lanes (in powers of 2) are provided.
These routines are based on the scalar versions of the math routines in
libm/common, libm/math and libm/mathfp. They make extensive use of the GCC
C vector extensions and GCN-specific builtins in GCC.