krb5: add prototype to silence clang warnings on mvsnprintf()

"error: format string is not a string literal"

Follow-up to 09230127589eccc7 which made the warning appear

Assisted-by: Viktor Szakats
Closes #12803

diff --git a/lib/krb5.c b/lib/krb5.c
index b334ae2f401241ed279e2b5b074c543d422dbc95..4db19fb27fa6bb96609f2049352b983b76d1ab8d 100644 (file)
--- a/lib/krb5.c
+++ b/lib/krb5.c
@@ -434,6 +434,9 @@ static char level_to_char(int level)
 
 /* Send an FTP command defined by |message| and the optional arguments. The
    function returns the ftp_code. If an error occurs, -1 is returned. */
+static int ftp_send_command(struct Curl_easy *data, const char *message, ...)
+  CURL_PRINTF(2, 3);
+
 static int ftp_send_command(struct Curl_easy *data, const char *message, ...)
 {
   int ftp_code;