perf tools: Fix mmap2 event allocation in synthesize code

perf_event__synthesize_mmap_events() issues mmap2 events, but the memory
of that event is allocated using:

mmap_event = malloc(sizeof(mmap_event->mmap) + machine->id_hdr_size);

If path of mmap source file is long (near PATH_MAX), random crash would
happen. Should use sizeof(mmap_event->mmap2).

Fix two memory allocations.

Signed-off-by: Wang Nan <[e-mail]>
Reviewed-by: Masami Hiramatsu <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: He Kuang <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Zefan Li <[e-mail]>
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/event.c

···
 	if (comm_event == NULL)
 		goto out;
 
-	mmap_event = malloc(sizeof(mmap_event->mmap) + machine->id_hdr_size);
+	mmap_event = malloc(sizeof(mmap_event->mmap2) + machine->id_hdr_size);
 	if (mmap_event == NULL)
 		goto out_free_comm;
 
···
 	if (comm_event == NULL)
 		goto out;
 
-	mmap_event = malloc(sizeof(mmap_event->mmap) + machine->id_hdr_size);
+	mmap_event = malloc(sizeof(mmap_event->mmap2) + machine->id_hdr_size);
 	if (mmap_event == NULL)
 		goto out_free_comm;