perf trace: Fix exclusion of not available syscall names from selector list

We were just skipping the syscalls not available in a particular
architecture without reflecting this in the number of entries in the
ev_qualifier_ids.nr variable, fix it.

This was done with the most minimalistic way, reusing the index variable
'i', a followup patch will further clean this by making 'i' renamed to
'nr_used' and using 'nr_allocated' in a few more places.
Reported-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Fixes: 04c41bcb ("perf trace: Skip unknown syscalls when expanding strace like syscall groups")
Link: https://lkml.kernel.org/r/20190613181514.GC1402@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -1527,9 +1527,9 @@ static int trace__read_syscall_info(struct trace *trace, int id)
 
 static int trace__validate_ev_qualifier(struct trace *trace)
 {
-	int err = 0, i;
+	int err = 0;
 	bool printed_invalid_prefix = false;
-	size_t nr_allocated;
+	size_t nr_allocated, i;
 	struct str_node *pos;
 
 	trace->ev_qualifier_ids.nr = strlist__nr_entries(trace->ev_qualifier);
@@ -1574,7 +1574,7 @@ static int trace__validate_ev_qualifier(struct trace *trace)
 			id = syscalltbl__strglobmatch_next(trace->sctbl, sc, &match_next);
 			if (id < 0)
 				break;
-			if (nr_allocated == trace->ev_qualifier_ids.nr) {
+			if (nr_allocated == i) {
 				void *entries;
 
 				nr_allocated += 8;
@@ -1587,11 +1587,11 @@ static int trace__validate_ev_qualifier(struct trace *trace)
 				}
 				trace->ev_qualifier_ids.entries = entries;
 			}
-			trace->ev_qualifier_ids.nr++;
 			trace->ev_qualifier_ids.entries[i++] = id;
 		}
 	}
 
+	trace->ev_qualifier_ids.nr = i;
 out:
 	if (printed_invalid_prefix)
 		pr_debug("\n");