This commit moves the various vload and vstore builtins (including
vload_half, vloada_half, etc.) to the CLC library.
This is almost entirely a code move and does not make any attempt to
clean up or optimize the definitions of these builtins. There is no
change to any of the targets' builtin libraries, except that the vstore
helper rounding functions are now internalized.
Cleanups can come in future work. The new CLC declarations and new
OpenCL wrappers show how these CLC implementations could be defined more
simply. The builtins could probably also be vectorized in future work;
right now all of the 'half' versions for both vload and vstore are
essentially scalarized.
b474c3f69e