Add missing parenthesis around btop and ptob macros to ensure
operation ordering is preserved after expansion.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#660
0cefc9dbcd