Squid-3 compile warning after latest comm.cc changes

[Henrik Nordstrom]

Revision 8905:

src/comm.cc: In function 'int comm_connect_addr(int, const IPAddress&)':
src/comm.cc:1144: warning: passing NULL to non-pointer argument 2 of
'void* memset(void*, int, size_t)'
make[1]: *** [comm.lo] Error 1