[OpenCL] Add as_size/ptrdiff/intptr/uintptr_t operators

size_t and friends are built-in scalar data types and s6.4.4.2 of the
OpenCL C Specification says the as_type() operator must be available
for these data types.

Differential Revision: https://reviews.llvm.org/D98959

GitOrigin-RevId: 35bc7569f8ad8e76d36560386bbc45ca40716410
2 files changed