Fix some of the netperf socklen_t warnings.

Another mistake in our config.h, for some reason.

Change-Id: I680a25435870b8fc4f7909ec038cb41ea1afc1ad
diff --git a/config.h b/config.h
index f20173d..07e490c 100644
--- a/config.h
+++ b/config.h
@@ -394,7 +394,7 @@
 /* #undef const */
 
 /* type to use in place of socklen_t if not defined */
-#define netperf_socklen_t unsigned
+#define netperf_socklen_t socklen_t
 
 /* Define to `long int' if <sys/types.h> does not define. */
 /* #undef off_t */