Andrew,
    If there are multi kprobes on the same probepoint, there
will be one extra aggr_kprobe on the head of kprobe list.
The aggr_kprobe has aggr_post_handler/aggr_break_handler
whether the other kprobe post_hander/break_handler is NULL
or not. This patch modifies this, only when there is one or
more kprobe in the list whose post_handler is not NULL,
post_handler of aggr_kprobe will be set as aggr_post_handler.

Signed-off-by: bibo, mao <bibo.mao@intel.com>

Thanks
bibo,mao