Defines starting with `p' in bsd/ufs/ufs

• PGRD bsd/ufs/ufs/ufs_readwrite.c:70
• PGRD_S bsd/ufs/ufs/ufs_readwrite.c:71
• PGWR bsd/ufs/ufs/ufs_readwrite.c:72
• PGWR_S bsd/ufs/ufs/ufs_readwrite.c:73