Restore the longer form of the _Generic.  The short form does not work in C++.
Include stdint.h to fix build.

Pointed by:	Olivier Cochard-Labbé
Explicitely include <machine/pcb.h>, so that we get the definition of
struct pcb.

Submitted by:	Zbyszek Bodek <zbb@semihalf.com>
Pointy hat to: 	cognet
Fix a possible NULL-pointer dereference on the pfsync(4) reconfiguration.

Reported by:	Eugene M. Zheganin