qemu-log: Add GCC format attribute

The new inline function qemu_log_vprintf should use this attribute.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/qemu-log.h b/qemu-log.h
index 2ed19d1..4cdc7c7 100644
--- a/qemu-log.h
+++ b/qemu-log.h
@@ -51,7 +51,8 @@
 
 /* vfprintf-like logging function
  */
-static inline void qemu_log_vprintf(const char *fmt, va_list va)
+static inline void GCC_FMT_ATTR(1, 0)
+qemu_log_vprintf(const char *fmt, va_list va)
 {
     if (qemu_logfile) {
         vfprintf(qemu_logfile, fmt, va);