perf trace: Prepare the strarray scnprintf method for reuse

Right now when an index passed to that method has no string associated
it'll print the index as a decimal number, prepare it so that we can use
it to print it in hex as well, for ioctls, for instance.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-nsvy06sqj64qvnkmzvwxsx2v@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -60,18 +60,25 @@ struct strarray {
 	.entries = array, \
 }
 
-static size_t syscall_arg__scnprintf_strarray(char *bf, size_t size,
+static size_t __syscall_arg__scnprintf_strarray(char *bf, size_t size,
+						const char *intfmt,
 					        struct syscall_arg *arg)
 {
 	struct strarray *sa = arg->parm;
 	int idx = arg->val - sa->offset;
 
 	if (idx < 0 || idx >= sa->nr_entries)
-		return scnprintf(bf, size, "%d", arg->val);
+		return scnprintf(bf, size, intfmt, arg->val);
 
 	return scnprintf(bf, size, "%s", sa->entries[idx]);
 }
 
+static size_t syscall_arg__scnprintf_strarray(char *bf, size_t size,
+					      struct syscall_arg *arg)
+{
+	return __syscall_arg__scnprintf_strarray(bf, size, "%d", arg);
+}
+
 #define SCA_STRARRAY syscall_arg__scnprintf_strarray
 
 static size_t syscall_arg__scnprintf_fd(char *bf, size_t size,