perf tests: Make objdump disassemble zero blocks

perf tests: Make objdump disassemble zero blocks

Add -z parameter to avoid skipping zero blocks:

 ffffffff816704fe <sysret_check+0x4b>:
 ffffffff816704fe:  7b 34         jnp ffffffff81670534 <sysret_signal+0x1c>
       ...
 ffffffff81670501 <sysret_careful>:
 ffffffff81670501:  0f ba e2 03   bt  $0x3,%edx
 ffffffff81670505:  73 11         jae ffffffff81670518 <sysret_signal>

Signed-off-by: Jan Stancek <jstancek@redhat.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/130c6267fbdb9af506633a9efa06f3269ff5bd2c.1441275982.git.jstancek@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>