bugfix: Fix typo in anchor mode comparison. (Probably asymptomatic.)
bugfix: Fix typo in anchor mode comparison. (Probably asymptomatic.)

This was discovered while fuzzing to check capture behavior, and like a
copy-paste issue. I have not been able to find any cases where it leads
to incorrect behavior on the current branch, but once capture matching
is integrated it can lead to inconsistent capture bounds. There will be
a regression test integrated along with the capture behavior.

The minimal case I've found is `$|^|.$` with the input of "x", which
should match with the bounds (0,0) for match group zero but instead
matches (0,1). The incorrect comparison operator in `ast_expr_cmp`'s
case for `AST_EXPR_ANCHOR` causes it to tread the `$` and `^` ALT
sub-branches as equal, deduplication during `ast_rewrite.c`'s
`deduplicate_alt` incorrectly discards the `^` sub-branch, and this
causes the `.$` to match "x" instead of the `^`, so match group zero
includes the `.` within its bounds rather than it matching the empty
string with an ignored suffix.

katef/libfsm,katef/libfsm,katef/libfsm,katef/libfsm,katef/libfsm