perf tools: Handle -h and -v options

Adding handling for '-h' and '-v' options to invoke help and version
command respectively.

Current behaviour is:

   $ perf -v
   Unknown option: -v

    Usage: perf [--version] [--help] [OPTIONS] COMMAND [ARGS]
   $ perf -h
   Unknown option: -h

    Usage: perf [--version] [--help] [OPTIONS] COMMAND [ARGS]

New behaviour:

  $ perf -h

   usage: perf [--version] [--help] [OPTIONS] COMMAND [ARGS]

   The most commonly used perf commands are:
     annotate        Read perf.data (created by perf record) and display annotated code
     archive         Create archive with object files with build-ids found in perf.data file
     bench           General framework for benchmark suites
   ...

  $ perf -v
  perf version 4.3.rc3.gc99e32

Updated man page.
Requested-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1444068369-20978-10-git-send-email-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf.txt

@@ -27,6 +27,14 @@ OPTIONS
 	Setup buildid cache directory. It has higher priority than
 	buildid.dir config file option.
 
+-v::
+--version::
+  Display perf version.
+
+-h::
+--help::
+  Run perf help command.
+
 DESCRIPTION
 -----------
 Performance counters for Linux are a new kernel-based subsystem

tools/perf/perf.c

@@ -161,6 +161,20 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
 		if (!strcmp(cmd, "--help") || !strcmp(cmd, "--version"))
 			break;
 
+		/*
+		 * Shortcut for '-h' and '-v' options to invoke help
+		 * and version command.
+		 */
+		if (!strcmp(cmd, "-h")) {
+			(*argv)[0] = "--help";
+			break;
+		}
+
+		if (!strcmp(cmd, "-v")) {
+			(*argv)[0] = "--version";
+			break;
+		}
+
 		/*
 		 * Check remaining flags.
 		 */