trace-cmd: Add msg_buf_len() function

Factor out common code computing message buffer length in a function.

No changes in behavior intended.

Link: http://lore.kernel.org/linux-trace-devel/20190315153326.5602-4-kaslevs@vmware.com

Signed-off-by: Slavomir Kaslev <kaslevs@vmware.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
1 file changed