Pull up the following revisions, requested by msaitoh in ticket #1734:

sys/dev/pci/ixgbe/ixgbe.c 1.264,1.269,1.272,
1.306 via patch

Four INTx related fixes:
- Fix a bug that the all interrupt sources are enabled when the
  interface is UP and the INTx line is shared with other devices.
- Fix a bug that it might incorrectly enable interrupt when
  IFF_RUNNING is not set.
- Don't process TX/RX if a queue interrupt isn't occurred.
- Increment legacy interrupt counter after checking INTx sharing.

(martin)