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

• PGRD bsd/ufs/ufs/ufs_readwrite.c:73
• PGRD_S bsd/ufs/ufs/ufs_readwrite.c:74
• PGWR bsd/ufs/ufs/ufs_readwrite.c:75
• PGWR_S bsd/ufs/ufs/ufs_readwrite.c:76