dtrace: implement tracemem optional third arg (dyn size)

dtrace: implement tracemem optional third arg (dyn size)

Solaris DTrace added a third, optional argument, dynamic size.
Here we implement this for Linux, including introducing the
new user-visible arguments
DTRACE_TRACEMEM_STATIC
DTRACE_TRACEMEM_DYNAMIC
DTRACE_TRACEMEM_SIZE
DTRACE_TRACEMEM_SSIZE
as well as refactoring the
dt_print_bytes() raw label, making it its own function
dt_print_rawbytes().

Orabug: 26223475

Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
Reviewed-by: Tomas Jedlicka <tomas.jedlicka@oracle.com>