HAVE_ARPA_NAMESER_COMPAT_H on Debian 9.5 64-bit

Clone and build:

```
git clone https://github.com/handshake-org/libhns
cd libhns
./buildconf
./configure
make
```

Output of interest:

```
CC hdig-hdig.o
hdig.c:150:17: error: ‘T_TLSA’ undeclared here (not in a function)
{ "TLSA", T_TLSA },
^~~~~~
hdig.c:151:17: error: ‘T_SMIMEA’ undeclared here (not in a function)
{ "SMIMEA", T_SMIMEA },
^~~~~~~~
hdig.c:152:19: error: ‘T_OPENPGPKEY’ undeclared here (not in a function)
{ "OPENPGPKEY", T_OPENPGPKEY },
^~~~~~~~~~~~
Makefile:1739: recipe for target 'hdig-hdig.o' failed
```

These values are defined in nameser.h, and conditionalized on constants in hns_config.h.

Edit hns_config.h so that these constants are not defined:

```
/* Define to 1 if you have the header file. */
//#define HAVE_ARPA_NAMESER_COMPAT_H 1

/* Define to 1 if you have the header file. */
//#define HAVE_ARPA_NAMESER_H 1
```

The code now compiles OK.

But arpa/nameser.h and arpa/nameser_compat.h exists:

```
$ ls /usr/include/arpa
ftp.h inet.h nameser_compat.h nameser.h telnet.h tftp.h
```

The T_ types used in htdig.c are not defined in them, though.