perf version: Add man page

Since a new option '--build-options' is created for 'perf version', so
we need to document it.

Signed-off-by: Jin Yao <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Jin Yao <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/perf-version.txt

···
+perf-version(1)
+===============
+
+NAME
+----
+perf-version - display the version of perf binary
+
+SYNOPSIS
+--------
+'perf version' [--build-options]
+
+DESCRIPTION
+-----------
+With no options given, the 'perf version' prints the perf version
+on the standard output.
+
+If the option '--build-options' is given, then the status of
+compiled-in libraries are printed on the standard output.
+
+OPTIONS
+-------
+--build-options::
+        Prints the status of compiled-in libraries on the
+        standard output.