perf string: Export asprintf__tp_filter_pids()

Will be used directly in 'perf trace' for setting up the command line
argv array to pass to cmd_record, as this was how 'perf trace record'
was implemented, following the model used in 'perf kvm record', 'perf
sched record', etc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-w3cuwjs63lxf5zpryy3145uv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/evlist.c

@@ -21,6 +21,7 @@
 #include "../perf.h"
 #include "asm/bug.h"
 #include "bpf-event.h"
+#include "util/string2.h"
 #include <signal.h>
 #include <unistd.h>
 #include <sched.h>
@@ -959,7 +960,7 @@ int perf_evlist__append_tp_filter(struct evlist *evlist, const char *filter)
 	return err;
 }
 
-static char *asprintf__tp_filter_pids(size_t npids, pid_t *pids)
+char *asprintf__tp_filter_pids(size_t npids, pid_t *pids)
 {
 	char *filter;
 	size_t i;