Macros starting with 'f' in ufs

• fragnum ufs/fs.h:401
• fragoff ufs/fs.h:385
• fragroundup ufs/fs.h:395
• fragstoblks ufs/fs.h:397
• freespace ufs/fs.h:410
• fsbtodb ufs/fs.h:331
• fs_cs ufs/fs.h:251
• fs_postbl ufs/fs.h:237
• fs_rotbl ufs/fs.h:241