Add printf format attribute for vasprintf().

(closes issue #12729)
Reported by: snuffy
Patches:
      bug_12729.diff uploaded by snuffy (license 35)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@118556 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/compat.h

@@ -110,7 +110,7 @@ int unsetenv(const char *name);
 #endif
 
 #if !defined(HAVE_VASPRINTF) && !defined(__AST_DEBUG_MALLOC)
-int vasprintf(char **strp, const char *fmt, va_list ap);
+int __attribute__ ((format (printf, 2, 0))) vasprintf(char **strp, const char *fmt, va_list ap);
 #endif
 
 #ifndef HAVE_STRLCAT