MFC r267226:
Initialize the pbuf counter for directio using SYSINIT.
Mark ffs_rawread.c as requiring both ffs and directio options to be
compiled into the kernel. Add ffs_rawread.c to the list of ufs.ko
module' sources.

MFC r267226:
Initialize the pbuf counter for directio using SYSINIT.
Mark ffs_rawread.c as requiring both ffs and directio options to be
compiled into the kernel. Add ffs_rawread.c to the list of ufs.ko
module' sources.