Changes

[mlir] Remove a number of methods from mlir::OpState that just forward to mlir::Operation. All call sites have been converted in previous changes.

[OpenCL] Add clang extension for function pointers.

The new clang internal extension '__cl_clang_function_pointers'
allows use of function pointers and other features that have
the same functionality:
- Use of member function pointers;
- Unrestricted use of references to functions;
- Virtual member functions.

This not a vendor extension and therefore it doesn't require any
special target support. Exposing this functionality fully
will require vendor or Khronos extension.

Tags: #clang

Differential Revision: https://reviews.llvm.org/D94021

[OpenCL] Add clang extension for variadic functions.

With the internal clang extension '__cl_clang_variadic_functions'
variadic functions are accepted by the frontend.

This is not a fully supported vendor/Khronos extension
as it can only be used on targets with variadic prototype
support or in metaprogramming to represent functions with
generic prototype without calling such functions in the
kernel code.

Tags: #clang

Differential Revision: https://reviews.llvm.org/D94027