compile warning in recent import dhcp-client

[csj]

We didn't define PTRSIZE_64BIT in the 64bit platform. When I compile it in 
Alpha, I got a warning.
In common/icmp.c, around line 174:
#ifdef PTRSIZE_64BIT
        icmp.icmp_id = (((u_int32_t)(u_int64_t)addr) ^
                        (u_int32_t)(((u_int64_t)addr) >> 32));
#else
        icmp.icmp_id = (u_int32_t)addr;   <=== this line generates the 
warning.
#endif

Should we define this constant in the Makefile?

Jun Su