Extend libclc remangler to support `[u]int64_t` types

The addition of image related entries in libclc discovered a need for extra remangling done in the [libclc remangler](https://github.com/intel/llvm/tree/sycl/libclc/utils/libclc-remangler).

Specifically, the remangler needs to be able to handle `[u]int64_t` that, depending on the OS, can be represented as either `[unsigned] long int` or `[unsigned] long long`.

A temporary CMake workaround is in place, please consult the [PR](https://github.com/intel/llvm/pull/11052) for details.