perf tools: Fix missing string field printing in perf trace

perf tools: Fix missing string field printing in perf trace

Some string fields are not printed because of a missing printf
in the post-processing.

Before:
	    perf-10070 [000]     0.000000: sched_switch: task :10070 [120] (R) ==> :5720 [120]
           geany-5720  [000]     0.000000: sched_switch: task :5720 [120] (S) ==> :10070 [120]
            perf-10070 [000]     0.000000: sched_switch: task :10070 [120] (R) ==> :5720 [120]
           geany-5720  [000]     0.000000: sched_switch: task :5720 [120] (S) ==> :10070 [120]
          <idle>-0     [000]     0.000000: sched_switch: task :0 [140] (R) ==> :361 [115]

After:
	    perf-10070 [000]     0.000000: sched_switch: task perf:10070 [120] (R) ==> geany:5720 [120]
           geany-5720  [000]     0.000000: sched_switch: task geany:5720 [120] (S) ==> perf:10070 [120]
            perf-10070 [000]     0.000000: sched_switch: task perf:10070 [120] (R) ==> geany:5720 [120]
           geany-5720  [000]     0.000000: sched_switch: task geany:5720 [120] (S) ==> perf:10070 [120]
          <idle>-0     [000]     0.000000: sched_switch: task swapper:0 [140] (R) ==> kondemand/1:361 [115]

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1251427567-10551-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>