continue instead of return

If using only Class B traffic clean up will fail as tx_ring for Class A has nothing to be cleaned up and function returns. So call continue to check on Class B.
igb_xmit: sem_post on ENOSPC

igb_xmit is returning ENOSPC without releasing the semaphore at the moment. 

So I added an unlock label and an error variable. So in case of ENOSPC the semaphore is unlocked before returning.
Merge pull request #58 from prabhakarlad/maap

trivial fixes + top level makefile
Merge pull request #59 from heinemml/patch-2

igb_clean: continue instead of return
Merge pull request #60 from heinemml/patch-3

igb_xmit: sem_post on ENOSPC
Enable parsing of VLAN-tagged packages

If ethertype is 0x8100 also check dot1q type for 0x22f0.

Signed-off-by: Schettke, Marc <schettke@ms2.info>