Add missing <stdarg.h> include in <bsd/err.h>
diff --git a/include/bsd/err.h b/include/bsd/err.h
index b8f9c82..d60158e 100644
--- a/include/bsd/err.h
+++ b/include/bsd/err.h
@@ -28,6 +28,7 @@
#define LIBBSD_ERR_H
#include <err.h>
+#include <stdarg.h>
extern void warnc (int code, const char *format, ...);
extern void vwarnc (int code, const char *format, va_list ap);