Add file hashing helpers

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/Makefile b/Makefile
index 7c79e91..1380c02 100644
--- a/Makefile
+++ b/Makefile
@@ -7,7 +7,7 @@
 SCRIPTS = fio_generate_plots
 OBJS = gettime.o fio.o ioengines.o init.o stat.o log.o time.o filesetup.o \
 	eta.o verify.o memory.o io_u.o parse.o mutex.o sem.o options.o \
-	rbtree.o diskutil.o fifo.o blktrace.o smalloc.o
+	rbtree.o diskutil.o fifo.o blktrace.o smalloc.o filehash.o
 
 OBJS += crc/crc7.o
 OBJS += crc/crc16.o