libtraceevent: Man pages for libtraceevent event print related API

Added new man page, describing tep_print_event() libtraceevent API.
Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/linux-trace-devel/20190801075012.22098-1-tz.stoyanov@gmail.com
Link: http://lore.kernel.org/lkml/20190919212541.553160178@goodmis.orgSigned-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/Documentation/libtraceevent-event_print.txt

+libtraceevent(3)
+================
+
+NAME
+----
+tep_print_event - Writes event information into a trace sequence.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+*#include <trace-seq.h>*
+
+void *tep_print_event*(struct tep_handle pass:[*]_tep_, struct trace_seqpass:[*]_s_, struct tep_record pass:[*]_record_, const char pass:[*]_fmt_, _..._)
+--
+
+DESCRIPTION
+-----------
+
+The _tep_print_event()_ function parses the event information of the given
+_record_ and writes it into the trace sequence _s_, according to the format
+string _fmt_. The desired information is specified after the format string.
+The _fmt_ is printf-like format string, following arguments are supported:
+[verse]
+--
+	TEP_PRINT_PID, "%d"  - PID of the event.
+	TEP_PRINT_CPU, "%d"  - Event CPU.
+	TEP_PRINT_COMM, "%s" - Event command string.
+	TEP_PRINT_NAME, "%s" - Event name.
+	TEP_PRINT_LATENCY, "%s" - Latency of the event. It prints 4 or more
+			fields - interrupt state, scheduling state,
+			current context, and preemption count.
+			Field 1 is the interrupt enabled state:
+				d : Interrupts are disabled
+				. : Interrupts are enabled
+				X : The architecture does not support this
+				    information
+			Field 2 is the "need resched" state.
+				N : The task is set to call the scheduler when
+				    possible, as another higher priority task
+				    may need to be scheduled in.
+				. : The task is not set to call the scheduler.
+			Field 3 is the context state.
+				. : Normal context
+				s : Soft interrupt context
+				h : Hard interrupt context
+				H : Hard interrupt context which triggered
+				    during soft interrupt context.
+				z : NMI context
+				Z : NMI context which triggered during hard
+				    interrupt context
+			Field 4 is the preemption count.
+				. : The preempt count is zero.
+			On preemptible kernels (where the task can be scheduled
+			out in arbitrary locations while in kernel context), the
+			preempt count, when non zero, will prevent the kernel
+			from scheduling out the current task. The preempt count
+			number is displayed when it is not zero.
+			Depending on the kernel, it may show other fields
+			(lock depth, or migration disabled, which are unique to
+			specialized kernels).
+	TEP_PRINT_TIME, %d - event time stamp. A divisor and precision can be
+			specified as part of this format string:
+			"%precision.divisord". Example:
+			"%3.1000d" - divide the time by 1000 and print the first
+			3 digits before the dot. Thus, the time stamp
+			"123456000" will be printed as "123.456"
+	TEP_PRINT_INFO, "%s" - event information.
+	TEP_PRINT_INFO_RAW, "%s" - event information, in raw format.
+
+--
+EXAMPLE
+-------
+[source,c]
+--
+#include <event-parse.h>
+#include <trace-seq.h>
+...
+struct trace_seq seq;
+trace_seq_init(&seq);
+struct tep_handle *tep = tep_alloc();
+...
+void print_my_event(struct tep_record *record)
+{
+	trace_seq_reset(&seq);
+	tep_print_event(tep, s, record, "%16s-%-5d [%03d] %s %6.1000d %s %s",
+			TEP_PRINT_COMM, TEP_PRINT_PID, TEP_PRINT_CPU,
+			TEP_PRINT_LATENCY, TEP_PRINT_TIME, TEP_PRINT_NAME,
+			TEP_PRINT_INFO);
+}
+...
+--
+
+FILES
+-----
+[verse]
+--
+*event-parse.h*
+	Header file to include in order to have access to the library APIs.
+*trace-seq.h*
+	Header file to include in order to have access to trace sequences related APIs.
+	Trace sequences are used to allow a function to call several other functions
+	to create a string of data to use.
+*-ltraceevent*
+	Linker switch to add when building a program that uses the library.
+--
+
+SEE ALSO
+--------
+_libtraceevent(3)_, _trace-cmd(1)_
+
+AUTHOR
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
+*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
+--
+REPORTING BUGS
+--------------
+Report bugs to  <linux-trace-devel@vger.kernel.org>
+
+LICENSE
+-------
+libtraceevent is Free Software licensed under the GNU LGPL 2.1
+
+RESOURCES
+---------
+https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git