ia64: perfmon update.

ia64: perfmon update.

Here is a ChangeLog for the patch:

        - The perfmon core will invoke the sampling module handler
          routine once for each overflowed PMD. When multiple PMDs
          overflow at the same time (with the same PMU interrupt),
          then up to 64 distinct calls can happen. A common timestamp
          parameter allows the module to identify this kind of
          entries.

        - Changed the module ovfl_ctrl arguments to simplify the reset
          field. Now it is a simple boolean.

        - Updated perfmon.h to convert the "set" field to ushort from
          uint.  Other structure updates to get better layout.

        - Update perfmon_default_smpl.h to reflect the change in
          overflow processing mentioned above.

        - Cleanup some state checking code to use switch-case instead
          of if-then with macros. Make the code more readable and
          easier to optmize for gcc. Thanks to David for the
          suggestion.

        - Added extra safety checks on pfm_context_load() to verify
          that the task actually exists.

        - The default sampling format module now supports the
          fmt_restart_active callbacks. Patch from David.