libtraceevent: Add tep_get_sub_buffer_data_size()

Add an API to be able to read the header page file and return the data size of
the sub buffers. This is the total size of the sub buffer minus the meta
data.

Link: https://lore.kernel.org/linux-trace-devel/20231226131339.7b0b727c@gandalf.local.home

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
4 files changed