The main sources of warnings were:
* Printing of a `size_t` which requires the `%zu` specifier.
* Printing of `cl_long`/`cl_ulong` which is now done using the
`PRI*64` macros to ensure portability across 32 and 64-bit builds.
Signed-off-by: Sven van Haastregt <sven.vanhaastregt@arm.com>