Fix memleak in SecEntity.host

[vokac]

Memory for SecEntity.host is already allocated by GetClientIPStr at

xrootd/src/XrdHttp/XrdHttpProtocol.cc

Lines 474 to 477 in 1578f62

	char *nfo = GetClientIPStr();
	if (nfo) {
	TRACEI(REQ, " Setting host: " << nfo);
	SecEntity.host = nfo;