Remove obsolete and incorrect FreeBSD version condition

The FreeBSD-related condition which enables custom round() implementation is incorrect: one must include <sys/param.h> to get __FreeBSD_version value, and since it's not included here, the check succeeds while it shouldn't. Before it worked somehow, but since python 3.7 it results in conflicting declarations of round(). The condition is also no longer needed since FreeBSD 5.3 is unsupported for 12 years.

Author: AMDmi3

psycopg/config.h

@@ -154,8 +154,7 @@ typedef unsigned __int64    uint64_t;
 #endif
 
 /* what's this, we have no round function either? */
-#if (defined(__FreeBSD__) && __FreeBSD_version < 503000) \
-    || (defined(_WIN32) && !defined(__GNUC__)) \
+#if (defined(_WIN32) && !defined(__GNUC__)) \
     || (defined(sun) || defined(__sun__)) \
         && (defined(__SunOS_5_8) || defined(__SunOS_5_9))