IMPORT: slz: use inttypes.h instead of stdint.h

IMPORT: slz: use inttypes.h instead of stdint.h

stdint.h is not as portable as inttypes.h. It doesn't exist at least
on AIX 5.1 and Solaris 7, while inttypes.h is present there and does
include stdint.h on platforms supporting it.

This is equivalent to libslz upstream commit e36710a ("slz: use
inttypes.h instead of stdint.h")