One failing unit test (iconv_read) on git master on OS X

On my Mac, all the tests are passing except for one: iconv_read. I'm willing to help debug it, if I could get a little bit of guidance on where to look…

I tried on an Ubuntu 10 system and I got a whole bunch of test failures, so I'll deal with those later.

```
=================================================================
   FreeTDS 0.92.dev.20130718: src/tds/unittests/test-suite.log
=================================================================

# TOTAL: 19
# PASS:  18
# SKIP:  0
# XFAIL: 0
# FAIL:  1
# XPASS: 0
# ERROR: 0

.. contents:: :depth: 2

FAIL: iconv_fread
=================

out 1024 bytes expected 4077
res 0 out_len 1024
```

iconv-related output from ./configure and link line:

```
checking for iconv... yes
checking how to link with libiconv... -liconv
checking for iconv declaration...
         extern size_t iconv (iconv_t cd, char * *inbuf, size_t *inbytesleft, char * *outbuf, size_t *outbytesleft);
…
/bin/sh ../../libtool  --tag=CC   --mode=link gcc -D_THREAD_SAFE  -g -O2 -Wdeclaration-after-statement -version-info 5:0:0    -o libsybdb.la -rpath /Users/marca/sw/lib dblib.lo dbutil.lo rpc.lo bcp.lo xact.lo dbpivot.lo   ../tds/libtds.la ../replacements/libreplacements.la  -liconv
```