perf report: Support folded callchain mode on --stdio

Add new call chain option (-g) 'folded' to print callchains in a line.
The callchains are separated by semicolons, and preceded by (absolute)
percent values and a space.

For example, the following 20 lines can be printed in 3 lines with the
folded output mode:

  $ perf report -g flat --no-children | grep -v ^# | head -20
      60.48%  swapper  [kernel.vmlinux]  [k] intel_idle
              54.60%
                 intel_idle
                 cpuidle_enter_state
                 cpuidle_enter
                 call_cpuidle
                 cpu_startup_entry
                 start_secondary

              5.88%
                 intel_idle
                 cpuidle_enter_state
                 cpuidle_enter
                 call_cpuidle
                 cpu_startup_entry
                 rest_init
                 start_kernel
                 x86_64_start_reservations
                 x86_64_start_kernel

  $ perf report -g folded --no-children | grep -v ^# | head -3
      60.48%  swapper  [kernel.vmlinux]  [k] intel_idle
  54.60% intel_idle;cpuidle_enter_state;cpuidle_enter;call_cpuidle;cpu_startup_entry;start_secondary
  5.88% intel_idle;cpuidle_enter_state;cpuidle_enter;call_cpuidle;cpu_startup_entry;rest_init;start_kernel;x86_64_start_reservations;x86_64_start_kernel

This mode is supported only for --stdio now and intended to be used by
some scripts like in FlameGraphs[1].  Support for other UI might be
added later.

[1] http://www.brendangregg.com/FlameGraphs/cpuflamegraphs.html

Requested-and-Tested-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1447047946-1691-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/callchain.h b/tools/perf/util/callchain.h
index fce8161..544d99a 100644
--- a/tools/perf/util/callchain.h
+++ b/tools/perf/util/callchain.h
@@ -24,7 +24,7 @@
 #define CALLCHAIN_RECORD_HELP  CALLCHAIN_HELP RECORD_MODE_HELP RECORD_SIZE_HELP
 
 #define CALLCHAIN_REPORT_HELP						\
-	HELP_PAD "print_type:\tcall graph printing style (graph|flat|fractal|none)\n" \
+	HELP_PAD "print_type:\tcall graph printing style (graph|flat|fractal|folded|none)\n" \
 	HELP_PAD "threshold:\tminimum call graph inclusion threshold (<percent>)\n" \
 	HELP_PAD "print_limit:\tmaximum number of call graph entry (<number>)\n" \
 	HELP_PAD "order:\t\tcall graph order (caller|callee)\n" \
@@ -43,7 +43,8 @@
 	CHAIN_NONE,
 	CHAIN_FLAT,
 	CHAIN_GRAPH_ABS,
-	CHAIN_GRAPH_REL
+	CHAIN_GRAPH_REL,
+	CHAIN_FOLDED,
 };
 
 enum chain_order {