this Forum aissts you with configuration of working ODBC connections from Oracle to foreign databases. When you have an issue building the foreign ODBC driver we could try to assist you when you provide more details which FreeTDS version you're going to compile on which platform, but it is always a better idea to check out the vendor's forums to get faster and better assistance.
When I try to compile the FreeTDS ODBC driver on a Solaris machine I first make sure that unixODBC is also installed, then I use these commands:
./configure prefix=/u01/odbc64/product/FreeTDS/0.91 with-unixodbc=/u01/odbc64/product/unixODBC/ enable-msdblib with-tdsver=8.0
sudo make install
=> and it works on my Solaris box.