atomics: Fix -Wformat warnings (#1519)
atomics: Fix -Wformat warnings (#1519)

The main sources of warnings were:

 * Printing of `i` which is a `size_t` requiring the `%zu` specifier.

 * Printing of `cl_long` which is now done using the `PRId64` macro
   to ensure portability across 32 and 64-bit builds.

Signed-off-by: Sven van Haastregt <c87899f97800fb9ac456b806e5f84934b5e9c197@arm.com>

Signed-off-by: Sven van Haastregt <c87899f97800fb9ac456b806e5f84934b5e9c197@arm.com>
KhronosGroup/OpenCL-CTS,KhronosGroup/OpenCL-CTS,KhronosGroup/OpenCL-CTS,KhronosGroup/OpenCL-CTS