commit 421d95b3ea introduced a compiler
warning on 32-bit systems about casting a pointer to an integer of a
different size. This commit removes the warning by casting the arguments
to snprintf in the same manner as the original VERIFY3_IMPL macro.
This has a minor impact on stack usage of individual functions, but the
VERIFY macros are used so frequently that their overhead may add up.
This macro declared two new local variables to cast its argument types.
Doing the typecast inline eliminates the need for these variables.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>