[vala/staging] posix: Add string.vprintf()

[Rico Tzschichholz <ricotz src gnome org>]

commit e2843eab6a85b0a8b652771f96109b0a838134ba
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sat Oct 19 20:06:51 2019 +0200

    posix: Add string.vprintf()

 vapi/posix.vapi | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/vapi/posix.vapi b/vapi/posix.vapi
index eb385bb70..477678804 100644
--- a/vapi/posix.vapi
+++ b/vapi/posix.vapi
@@ -268,6 +268,8 @@ public struct va_list {
 public class string {
        [PrintfFormat]
        public string printf (...);
+       [CCode (cname = "vprintf", cheader_filename = "stdarg.h")]
+       public string vprintf (va_list args);
 
        public string concat (...) {
                string result = this;