No variable spindle and spindle speed fix.

- When VARIABLE_SPINDLE output is disabled in config.h, the last commit
would keep the spindle enable pin disabled when spindle speed is not
defined (S0). This is now ignored and will enable with S0, as spindle
speed is ignored in this mode.

doc/log/commit_log_v0.9j.txt

@@ -1,3 +1,14 @@
+----------------
+Date: 2016-03-16
+Author: Sonny Jeon
+Subject: Soft limit handling bug fix
+
+- Soft limit errors were stuck in a feed hold without notifying the
+user why it was in a hold. When resumed, the soft limit error would
+kick in. Issue should be fixed to behave as intended to automatically
+hold and issue a soft limit alarm once the machine has come to a stop.
+
+
 ----------------
 Date: 2016-03-03
 Author: Sonny Jeon