inlining click: +10%

[Robert Morris]

If I take the output of click-devirtualize and cause g++ to inline it,
it gets about 10% faster. I first outlined some of the element code,
and also got rid of some (more) old hand-optimizations that got rid of
virtual function calls. So every element has a simple_action.

My benchmark is the following IP-like configuration, running at user
level:

e12 :: Discard;
e11 :: IPFragmenter(1500);
e10 :: DecIPTTL;
e9 :: FixIPSrc(2.0.0.1);
e8 :: IPGWOptions(2.0.0.1);
e7 :: CheckPaint(2);
e6 :: DropBroadcasts;
e5 :: GetIPAddress(16);
e4 :: CheckIPHeader();
e3 :: Strip(14);
e2 :: Paint(1);
e1 :: InfiniteSource(\<00 00 c0 ae 67 ef 00 00 00 00 00 00 08 00
45 00 00 28  00 00 00 00  40 11 77 c3  01 00 00 01  
02 00 00 02  13 69 13 69  00 14 d6 41  55 44 50 20  
70 61 63 6b  65 74 21 0a  04 00 00 00  01 00 00 00  
01 00 00 00  00 00 00 00  00 80 04 08  00 80 04 08  
53 53 00 00  53 53 00 00  05 00 00 00  00 10 00 00  
01 00 00 00  54 53 00 00  54 e3 04 08  54 e3 04 08  
d8 01 00 00>, 1000000, 5);

e1 -> e2
   -> e3
   -> e4
   -> e5
   -> e6
   -> e7
   -> e8
   -> e9
   -> e10
   -> e11
   -> e12; 

e7[1] -> Discard;