This is a crucial piece of information for SYBASE users:
If you are using the free, but old, 11.x client libs from sybase,
then compile with option "--with-sybase-ct=$SYBASE"
substitute $SYBASE with the appropriate directory name.
option --with-sybase (without ct) can somehow be used to talk to old MS-SQL servers, but only with the 11.x client libs.
If you are using free, or have legally obtained, 12.x client libs from sybase, then compile with option "--with-sybase-ct=$SYBASE/$SYBASE_OCS"
substitute $SYBASE/$SYBASE_OCS with the appropriate directory name.