The check for round failed during configure.  I included a bit of that in my second note above.  Here's a bit more of the output:

collect2: ld returned 1 exit status
configure:11989: $? = 1
configure: failed program was:
| /* confdefs.h */
| #define _GNU_SOURCE 1
| #define _NETBSD_SOURCE 1
<snip>
| /* Override any GCC internal prototype to avoid an error.
|    Use char because int might match the return type of a GCC
|    builtin and then its argument prototype would still apply.  */
| #ifdef __cplusplus
| extern "C"
| #endif
| char round ();
| /* The GNU C library defines this for functions which it implements
|     to always fail with ENOSYS.  Some functions are actually named
|     something starting with __ and the normal name is an alias.  */
| #if defined __stub_round || defined __stub___round
| choke me
| #endif
|
| int
| main ()
| {
| return round ();
|   ;
|   return 0;
| }
configure:11989: result: no