Can't get php5 to build on machines that have php4 or have had php4

[Edwin L. Culp]

Can't get php5 to build on machines that have php4 or have had php4.

I have php5 running with no problems on machines that I installed it 
initially but I've not been able to compile php5 on any machine that 
has or has had ( deleted with pkg_delete php4*).  I can't find the 
reason for the error that I get in all cases.

ext/standard/dns.lo(.text+0x131f): In function `zif_dns_get_record':
: undefined reference to `res_ninit'
ext/standard/dns.lo(.text+0x1365): In function `zif_dns_get_record':
: undefined reference to `res_nmkquery'
ext/standard/dns.lo(.text+0x138d): In function `zif_dns_get_record':
: undefined reference to `res_nsend'
ext/standard/dns.lo(.text+0x148f): In function `zif_dns_get_record':
: undefined reference to `res_nclose'
*** Error code 1

Stop in /usr/ports/lang/php5/work/php-5.0.4.
*** Error code 1

Thanks for any suggestions,

ed