add va_start/va_end.

src/libbio/bprint.c

diff --git a/src/libbio/bprint.c b/src/libbio/bprint.c
index 878bfb6..bfcb4a0 100644
--- a/src/libbio/bprint.c
+++ b/src/libbio/bprint.c
@@ -10,7 +10,9 @@
 
 	if(Bfmtinit(&f, bp) < 0)
 		return -1;
+	va_start(args, fmt);
 	n = fmtprint(&f, fmt, args);
+	va_end(args);
 	if(n > 0 && Bfmtflush(&f) < 0)
 		return -1;
 	return n;