Introduce prototype-style function definition for bzero.  This happened
upstream as part of:

commit ddcf6798d35beca3c4eec80ea448b57fd45558f4
Author: Wilco Dijkstra <wdijkstr@arm.com>
Date:   Fri Feb 27 14:41:46 2015 +0000

    Rather than using a C implementation of memset, directly call memset, which
    typically has a much faster optimized implementation.

diff --git a/string/bzero.c b/string/bzero.c
index b7a88ec9253bdf0c..c3276e7752935801 100644
--- a/string/bzero.c
+++ b/string/bzero.c
@@ -23,9 +23,7 @@
 
 /* Set N bytes of S to 0.  */
 void
-__bzero (s, len)
-     void *s;
-     size_t len;
+__bzero (void *s, size_t len)
 {
   long int dstp = (long int) s;
   const op_t zero = 0;