perf mem/c2c: Set PERF_SAMPLE_WEIGHT for LOAD_STORE events

Currently perf sets PERF_SAMPLE_WEIGHT flag only for mem load events.
Set it for combined load-store event as well which will enable recording
of load latency by default on arch that does not support independent
mem load event.

Also document missing -W in perf-record man page.

Signed-off-by: Ravi Bangoria <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ali Saidi <[e-mail]>
Cc: Ananth Narayan <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Joe Mario <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Kim Phillips <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Sandipan Das <[e-mail]>
Cc: Santosh Shukla <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/perf-record.txt

···
 The various filters must be specified as a comma separated list: --branch-filter any_ret,u,k
 Note that this feature may not be available on all processors.
 
+-W::
 --weight::
 Enable weightened sampling. An additional weight is recorded per sample and can be
 displayed with the weight and local_weight sort keys.  This currently works for TSX

tools/perf/builtin-c2c.c

···
 		 */
 		if (e->tag) {
 			e->record = true;
+			rec_argv[i++] = "-W";
 		} else {
 			e = perf_mem_events__ptr(PERF_MEM_EVENTS__LOAD);
 			e->record = true;

tools/perf/builtin-mem.c

···
 	    (mem->operation & MEM_OPERATION_LOAD) &&
 	    (mem->operation & MEM_OPERATION_STORE)) {
 		e->record = true;
+		rec_argv[i++] = "-W";
 	} else {
 		if (mem->operation & MEM_OPERATION_LOAD) {
 			e = perf_mem_events__ptr(PERF_MEM_EVENTS__LOAD);