[PATCH] Don't hardcode ioengine path

Use the prefix in the Makefile, so it can be packaged properly.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.h b/fio.h
index 64f3b2d..112736c 100644
--- a/fio.h
+++ b/fio.h
@@ -325,6 +325,7 @@
 extern int terse_output;
 extern FILE *f_out;
 extern FILE *f_err;
+extern char *fio_inst_prefix;
 
 extern struct thread_data *threads;