bug#17576: [PATCH] dfa: speed-up at initial state

[Paul Eggert]

I don't think we need to complicate the code to improve optimization 
with older compilers.  People who really care about performance will use 
newer compilers anyway.  So let's focus on 
0001-dfa-speed-up-at-initial-state.patch.

I confirmed your performance results on my platform: the change makes 
test case "k" about 60% faster and test case "l" about 14% slower.  At 
this point we're just in bugfix mode so this patch can wait.  It'd be 
nice if it didn't slow down the short-line case so much.  Also, I wonder 
how well this change works for "typical" searches.  (I realize that 
"typical" is hard to define....)