Fixed $cookie_ after a cookie without a name

Fixed $cookie_ after a cookie without a name

A cookie without a name, such as "a" in "Cookie: a; a=1", was skipped
together with the separator that follows it, so the next cookie was
skipped as well and $cookie_a was not found.  The userid module was
affected in the same way.

User agents send a cookie with an empty name as a bare value (RFC
6265bis, section 5.8.3), so such a token is a valid part of the Cookie
header.

The fix is to not consume the character that fails the "=" check.

The problem appeared in 899b44eab (0.1.29).