perf tools: Fix the bash completion for listing options of perf subcommand

The bash completion does not support listing options for 'perf
kvm|kmem|mem|lock|sched --<TAB>', where 'kvm|kmem|mem|lock|sched' are
all subcommands of perf.

Example:

Before this patch:

 $ perf kvm --<TAB>
 $

As shown above, the options of perf kvm does not come out.

After this patch:

 $ perf kvm --<TAB>
 --alloc    --caller   --input    --line     --raw-ip   --sort
 --verbose

As shown above, the options of perf kvm can come out now.

Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1426685758-25488-2-git-send-email-yunlong.song@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/perf-completion.sh

@@ -119,15 +119,18 @@ __perf_main ()
 	elif [[ $prev == "-e" && "${words[1]}" == @(record|stat|top) ]]; then
 		evts=$($cmd list --raw-dump)
 		__perfcomp_colon "$evts" "$cur"
-	# List subcommands for perf commands
-	elif [[ $prev == @(kvm|kmem|mem|lock|sched) ]]; then
-		subcmds=$($cmd $prev --list-cmds)
-		__perfcomp_colon "$subcmds" "$cur"
-	# List long option names
-	elif [[ $cur == --* ]];  then
-		subcmd=${words[1]}
-		opts=$($cmd $subcmd --list-opts)
-		__perfcomp "$opts" "$cur"
+	else
+		# List subcommands for perf commands
+		if [[ $prev == @(kvm|kmem|mem|lock|sched) ]]; then
+			subcmds=$($cmd $prev --list-cmds)
+			__perfcomp_colon "$subcmds" "$cur"
+		fi
+		# List long option names
+		if [[ $cur == --* ]];  then
+			subcmd=${words[1]}
+			opts=$($cmd $subcmd --list-opts)
+			__perfcomp "$opts" "$cur"
+		fi
 	fi
 }