Use GCC_FMT_ATTR (format checking)

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/slirp/slirp.h b/slirp/slirp.h
index 6c7488c..462292d 100644
--- a/slirp/slirp.h
+++ b/slirp/slirp.h
@@ -263,7 +263,7 @@
  long gethostid(void);
 #endif
 
-void lprint(const char *, ...);
+void lprint(const char *, ...) GCC_FMT_ATTR(1, 2);
 
 #ifndef _WIN32
 #include <netdb.h>