toolbox: turn on -Werror

- Deal with some signedness issues
- Deal with some size issues
- Deal with NULL pointer issues
- Deal with some -Wunused issues

Change-Id: I1479dd90d690084491bae3475f2c547833519a57
diff --git a/toolbox/cp/cp.c b/toolbox/cp/cp.c
index bd3c70e..e666453 100644
--- a/toolbox/cp/cp.c
+++ b/toolbox/cp/cp.c
@@ -95,12 +95,14 @@
 
 static int copy(char *[], enum op, int);
 
+#ifndef ANDROID
 static void
 progress(int sig __unused)
 {
 
 	pinfo++;
 }
+#endif
 
 int
 cp_main(int argc, char *argv[])