Fix two erroneous calls to strlcat()

[khorben]

strlcat() needs to be informed about the actual size of the buffer. Two
calls simply used the size expected, thus potentially allowing
stack-based buffer overflows.

There is no direct security impact in this case, since the code affected
is on the client side, and the input comes from configuration
information.

[khorben]

Sorry, I think this commit introduces a regression: the original intent was probably to append options->access_str only up to the / character. With this change, the code is safer but the contents after the / character will be added too, thus breaking this functionality. Please revert it for the moment :(

[mrash]

Done.