bug#17700: [PATCH] dfa: speed-up for a pattern that many atoms are catenated

[Paul Eggert]

Norihiro Tanaka wrote:
> BTW, even before make
> this change, dfamusts is terminated by NUL byte.

Yes, that's right, this patch doesn't affect whether the DFA code works 
correctly on NUL bytes.  There is a performance issue: if the pattern 
contains NUL bytes the DFA code doesn't operate as efficiently as it 
will does the pattern contains only non-NUL bytes.  But this performance 
issue is unaffected by the recent change.

It's low priority to fix the performance issue, but if we wanted to fix 
it among many other things we should use memmem instead of strstr.