mesa: Fix format specifier warning in mesa_DispatchComputeIndirect()

mesa: Fix format specifier warning in mesa_DispatchComputeIndirect()

Commit 1665d29ee3125743fd6daf3c43fc715f543d5669 introduced an incorrect
format specifier that operates on GLintptr indirect within the function
_mesa_DispatchComputeIndirect().

This patch mitigates the introduced GCC warning:

src/mesa/main/compute.c: In function '_mesa_DispatchComputeIndirect':
src/mesa/main/compute.c:53:7: warning: format '%d' expects argument of type 'int', but argument 3 has type 'GLintptr' [-Wformat=]
       _mesa_debug(ctx, "glDispatchComputeIndirect(%d)\n", indirect);
           ^

v2: Amend for Boyan Ding <boyan.j.ding@gmail.com> feedback.

Signed-off-by: Rhys Kidd <rhyskidd@gmail.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>