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

diff --git a/networking/libiproute/iptunnel.c b/networking/libiproute/iptunnel.c
index 2b17135..a936a42 100644
--- a/networking/libiproute/iptunnel.c
+++ b/networking/libiproute/iptunnel.c
@@ -482,7 +482,7 @@
 		    (p->i_key && p1.i_key != p->i_key))
 			continue;
 		print_tunnel(&p1);
-		puts("");
+		bb_putchar('\n');
 	}
 }
 
@@ -512,7 +512,7 @@
 		return -1;
 
 	print_tunnel(&p);
-	puts("");
+	bb_putchar('\n');
 	return 0;
 }