Fix return values in rm(1) and mv(1)

by setting rm_status to 1 if removing 1 file in the list fails.
Extend this to mv_status in mv(1).

fs.h

@@ -9,6 +9,7 @@ extern int cp_status;
 
 extern int rm_fflag;
 extern int rm_rflag;
+extern int rm_status;
 
 int cp(const char *, const char *);
 void rm(const char *);