BUG/MINOR: tools: url2sa reads ipv4 too far

BUG/MINOR: tools: url2sa reads ipv4 too far

The url2sa implementation is inconsitent when parsing an IPv4, indeed
url2sa() takes a <ulen> as a parameter where the call to url2ipv4() takes
a null terminated string. Which means url2ipv4 could try to read more
that it is supposed to.

This function is only used from a buffer so it never reach a unallocated
space. It can only cause an issue when used from the httpclient which
uses it with an ist.

This patch fixes the issue by copying everything in the trash and
null-terminated it.

Must be backported in all supported version.