Fix datetime precision causing milliseconds to not be read.

The datetime precision was no longer being read so the default was used.  This caused it to
read only up to seconds.

I had consolidated some code while fixing something else and missed an important "if" statement
that was specific to one of the instances.

Fixes mkleehammer#235

src/cnxninfo.cpp

@@ -75,7 +75,7 @@ inline void GetColumnSize(Connection* cnxn, SQLSMALLINT sqltype, int* psize)
     {
         // I believe some drivers are returning negative numbers for "unlimited" text fields,
         // such as FileMaker.  Ignore anything that seems too small.
-        if (columnsize >= 255)
+        if (columnsize >= 1)
             *psize = (int)columnsize;
     }