SIGNAL DUMP fails on FreeBSD

On FreeBSD 8.2, the control port command SIGNAL DUMP fails:

signal dump
250 OK
650 WARN control_signal_act(): Bug: Unrecognized signal number 30. 

This occurs because we use the platform's definition of SIGUSR1 (in this case, 30) in handle_control_signal in src/or/control.c, but control_signal_act in src/or/main.c expects the Linux-specific value 10. (This problem doesn't appear on Windows because src/or/or.h defines the signal values we use if the platform header files do not.)