[MINOR] acl: don't report valid acls as potential mistakes

Commit 404e8ab4615d564a74f92a0d3822b0292dd6224f introduced
smart checking for stupid acl typos. However, now haproxy shows
the warning even for valid acls, like this one:
	acl Cookie-X-NoAccel    hdr_reg(cookie) (^|\ |;)X-NoAccel=1(;|$)
1 file changed