Currently show_config() has a problem when user and system config files
have the same config variables i.e.:

  # cat ~/.perfconfig
  [top]
          children = false

When $(sysconfdir) is /usr/local/etc

  # cat /usr/local/etc/perfconfig
  [top]
          children = true

Before:

  # perf config --user --list
  top.children=false

  # perf config --system --list
  top.children=true

  # perf config --list
  top.children=true
   top.children=false

Because perf_config() can call show_config() each the config file (user
and system).  Fix it.

After:

  # perf config --user --list
  top.children=false

  # perf config --system --list
  top.children=true

  # perf config --list
  top.children=false
Signed-off-by: NTaeung Song <treeze.taeung@gmail.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1460620401-23430-3-git-send-email-treeze.taeung@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The '--system' option means $(sysconfdir)/perfconfig and '--user' means
$HOME/.perfconfig. If none is used, both system and user config file are
read.  E.g.:

    # perf config [<file-option>] [options]

    With an specific config file:

    # perf config --user | --system

    or both user and system config file:

    # perf config
Signed-off-by: NTaeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1455126685-32367-2-git-send-email-treeze.taeung@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move the subcommand-related files from perf to a new library named
libsubcmd.a.

Since we're moving files anyway, go ahead and rename 'exec_cmd.*' to
'exec-cmd.*' to be consistent with the naming of all the other files.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/c0a838d4c878ab17fee50998811612b2281355c1.1450193761.git.jpoimboe@redhat.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

The perf configuration file contains many variables to change various
aspects of each of its tools, including output, disk usage, etc.

But looking at the state of configuration is difficult and there's no
documentation about config variables except for the variables in
perfconfig.example exist.

So this patch adds a 'perf-config' command with a '--list' option.

    perf config [options]

    display current perf config variables.
    # perf config -l | --list
Signed-off-by: NTaeung Song <treeze.taeung@gmail.com>
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1447768424-17327-1-git-send-email-treeze.taeung@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>