Fix support of OS's like openBSD that use an older nameser.h,
this change reverts the defines to the older style which on other
systems is found in nameser_compat.h

Tested on openBSD 6.0, Debian 8

ASTERISK-26608 #close

Change-Id: Iffb36caab8c5aa9dece0ce2d009041f7b56cc86a