gcc-4.5 and 4.6 needs to be recompiled due to /usr/src/UPDATE: 20110608:

[Hartmann, O.]

Since the notice mentioned in /usr/src/UPDATE (20110608) both gcc-4.5 
and 4.6 seems to need to be recompiled. I tried some ports with 
"USE_FORTRAN= yes" setand they failed as with gcc-4.6. There was always 
an error reporting: undefined reference to __cpumask_t or similar.

Oliver