introduce bb_putchar(). saves ~1800 on uclibc (less on glibc).

diff --git a/networking/traceroute.c b/networking/traceroute.c
index 2d09c71..e8d486f 100644
--- a/networking/traceroute.c
+++ b/networking/traceroute.c
@@ -1322,7 +1322,7 @@
 				printf(" *");
 			(void)fflush(stdout);
 		}
-		putchar('\n');
+		bb_putchar('\n');
 		if (got_there ||
 		    (unreachable > 0 && unreachable >= nprobes - 1))
 			break;