[NET]: uninline skb_pull, de-bloats a lot

Allyesconfig (v2.6.24-mm1):

-28162  354 funcs, 3005 +, 31167 -, diff: -28162 --- skb_pull

Without number of debug related CONFIGs (v2.6.25-rc2-mm1):

-9697  338 funcs, 221 +, 9918 -, diff: -9697 --- skb_pull
skb_pull                      |  +44

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>