- Track whether TRST and/or SRST actually change:

    * If they're not changing, don't ask the JTAG adapter to do anything!
      (JTAG TCK/TMS ops might still be used to enter TAP_RESET though.)
    * Don't change their recorded values until after the adapter says it
      did so ... so fault paths can't leave corrupt state.
    * Detect and report jtag_execute_queue() failure mode
    * Only emit messages saying what really changed; this includes adding
      an omitted "deasserted TRST" message.
    * Only apply delays after deasserting SRST/TRST if we *DID* deassert!

 - Messages say "TLR" not "RESET", to be less confusing; there are many
   kinds of reset.  (Though "TLR" isn't quite ideal either, since it's
   the name of the TAP state being entered by TMS+TCK or TRST; it's at
   least non-ambiguous in context.)

So the main effect is to do only the work this routine was told to do;
and to have debug messaging make more sense.

git-svn-id: svn://svn.berlios.de/openocd/trunk@2621 b42882b7-edfa-0310-969c-e2dbd0fdcd60