Fix typo in safe_close() made while converting to debug framework

that prevented it from actually closing anything.

src/exec_pty.c

@@ -1263,5 +1263,5 @@ safe_close(int fd)
 	errno = EINVAL;
 	return -1;
     }
-    debug_return_int(fd);
+    debug_return_int(close(fd));
 }