Fix userinfo percent-encoding (#1367)

Fix userinfo percent-encoding (#1367)

%X expects an unsigned int, and that is what we were giving it. However,
to get to the correct unsigned int value from a (signed) char, one has
to cast to an unsigned char (or equivalent) first.

Broken since inception in commit 7b75100.

Also adjusted similar (commented out) ext_edirectory_userip_acl code.