S_IWRITE is an obsolete synonym for S_IWUSR, which Android does not define.

diff -u -r ../dropbear-2013.62/scp.c ./scp.c
--- ../dropbear-2013.62/scp.c	2013-12-03 14:39:15.000000000 +0100
+++ ./scp.c	2014-01-05 21:21:37.930812382 +0100
@@ -992,7 +992,7 @@
 			continue;
 		}
 		omode = mode;
-		mode |= S_IWRITE;
+		mode |= S_IWUSR;
 		if ((ofd = open(np, O_WRONLY|O_CREAT, mode)) < 0) {
 bad:			run_err("%s: %s", np, strerror(errno));
 			continue;